RSS

Most votes on android-layout questions 10

Most votes on android-layout questions 10. #91 Error inflating class fragment #92 Android - how to make a scrollable constraintlayout? #93 Border in shape XML #94 How to dismiss the dialog with click on outside of the dialog? #95 Preview layout with merge root tag in Intellij IDEA/Android Studio #96 What is android:weightSum in android, and how does it work? #97 Why are nested weights bad for performance? Alternatives? #98 java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference #99 ListView inside ScrollView is not scrolling on Android #100 One Activity and all other Fragments

Read all the top votes questions and answers in a single page.

#91: Error inflating class fragment (Score: 170)

Created: 2011-06-21 Last updated: 2016-07-06

Tags: android, android-layout, android-fragments

I get the Error

Unable to start activity ComponentInfo{de.androidbuch.activiti/de.androidbuch.activiti.task.Activity}: android.view.InflateException: Binary XML file line #11: Error inflating class fragment

when I switch via the portrait and the landscape mode. I’m using fragments. My xml is:

 <LinearLayout android:id="@+id/mainLayout"
               android:orientation="horizontal"
               android:layout_width="fill_parent"
               android:layout_height="wrap_content" >

    <ListView android:id="@+id/android:list"
              android:layout_height="wrap_content"
              android:layout_width="fill_parent"/> 

    <fragment android:id="@+id/fragmentDetails"
              android:layout_height="fill_parent"
              android:layout_width="fill_parent"
              class="de.androidbuch.activiti.task.TaskDetailsFragment"/> 
</LinearLayout>

If I switch via landscape and portrait mode everything works fine. But when I click on my fragment (and I can see my fragment) and then switch to the other mode I get the error. Any idea how I can solve it? Found some answers here but none of these helped me out…

06-21 14:55:05.600: ERROR/AndroidRuntime(7636): FATAL EXCEPTION: main
06-21 14:55:05.600: ERROR/AndroidRuntime(7636): java.lang.RuntimeException: Unable to start activity         
ComponentInfo{de.androidbuch.activiti/de.androidbuch.activiti.task.Activity}:   android.view.InflateException: Binary XML file line #11: Error inflating class fragment
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1736)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1752)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3097)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.ActivityThread.access$1600(ActivityThread.java:123)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:997)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.os.Looper.loop(Looper.java:126)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.ActivityThread.main(ActivityThread.java:3998)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at java.lang.reflect.Method.invokeNative(Native Method)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at java.lang.reflect.Method.invoke(Method.java:491)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at dalvik.system.NativeStart.main(Native Method)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636): Caused by: android.view.InflateException: Binary XML file line #11: Error inflating class fragment
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:688)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.view.LayoutInflater.rInflate(LayoutInflater.java:724)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.view.LayoutInflater.rInflate(LayoutInflater.java:727)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.view.LayoutInflater.inflate(LayoutInflater.java:479)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.view.LayoutInflater.inflate(LayoutInflater.java:391)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.view.LayoutInflater.inflate(LayoutInflater.java:347)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:227)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.Activity.setContentView(Activity.java:1771)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at de.androidbuch.activiti.task.TaskActivity.onCreate(TaskActivity.java:83)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1700)
06-21 14:55:05.600: ERROR/AndroidRuntime(7636):     ... 12 more

#91 Best answer 1 of Error inflating class fragment (Score: 132)

Created: 2012-02-06 Last updated: 2016-03-09

As hdemirchian said, make sure to use:

import android.support.v4.app.Fragment;

And also make sure that the Activity that is using the fragment(s) extends FragmentActivity instead of the regular Activity,

import android.support.v4.app.FragmentActivity;

to get the FragmentActivity class.

#91 Best answer 2 of Error inflating class fragment(Score: 103)

Created: 2013-02-28 Last updated: 2013-12-13

The exception android.view.InflateException: Binary XML file line: #... Error inflating class fragment might happen if you manipulate with getActivity() inside your fragment before onActivityCreated() get called. In such case you receive a wrong activity reference and can’t rely on that.

For instance the next pattern is wrong:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
        Bundle savedInstanceState) 
{
    final View view = inflater.inflate(R.layout..., container, false);
    
    Button button = getActivity().findViewById(R.id...);
    button.setOnClickListener(...); - another problem: button is null

    return view;
}

Correct pattern #1

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
        Bundle savedInstanceState) 
{
    final View view = inflater.inflate(R.layout..., container, false);
    
    Button button = view.findViewById(R.id...);
    button.setOnClickListener(...);

    return view;
}

Correct pattern #2

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    Button button = getActivity().findViewById(R.id...);
    button.setOnClickListener(...);
}

See also original question in stackoverflow

#92: Android - how to make a scrollable constraintlayout? (Score: 169)

Created: 2017-03-29 Last updated: 2019-05-12

Tags: android, android-layout, android-scrollview, android-constraintlayout

I want to make a layout that lets me scroll down using constraint layout, but I don’t know how to go about it. Should the ScrollView be the parent of the ConstraintLayout like this?

<?xml version="1.0" encoding="utf-8"?>

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true">

<android.support.constraint.ConstraintLayout
    android:id="@+id/Constraint"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

Or the other way around? Maybe someone can point me to a good tutorial on this or give an example, I can’t seem to find one.

Also, I don’t know if this is a bug or some configuration that I don’t have set up but I’ve seen images like this one :

enter image description here

where there are some components outside the blueprint “blue rectangle” yet they are visible, while on my side if I place a component on the “white space” I can’t see it or move it anywhere, and it appears on the component tree.

UPDATE :

I found a way to make the constraint layout scrollable in the design tool, using a horizontal guideline to push down the constraint layout border and extend it beyond the device, after that, you can use the guideline as the new bottom of the constraint layout to anchor the components.

#92 Best answer 1 of Android - how to make a scrollable constraintlayout? (Score: 90)

Created: 2017-05-04 Last updated: 2017-07-10

It seems that it is working, I don’t know what dependency you were working with but in this one

compile 'com.android.support.constraint:constraint-layout:1.0.2'

Is working, this is what I did

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    
    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        
        <android.support.design.widget.TextInputLayout
            android:id="@+id/til_input"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:hint="Escriba el contenido del archivo"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toLeftOf="@+id/btn_save"
            app:layout_constraintTop_toTopOf="@id/btn_save"
            app:layout_constraintVertical_chainStyle="spread">
            
            <EditText
                android:layout_width="match_parent"
                android:layout_height="match_parent" />
        </android.support.design.widget.TextInputLayout>
        
        <Button
            android:id="@+id/btn_save"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="onClickButtonSave"
            android:text="Guardar"
            app:layout_constraintLeft_toRightOf="@+id/til_input"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
        
        <TextView
            android:id="@+id/txt_content"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginTop="0dp"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/til_input"
            app:layout_constraintVertical_chainStyle="spread"
            app:layout_constraintVertical_weight="1" />
        
        <Button
            android:id="@+id/btn_delete"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:onClick="onClickButtonDelete"
            android:text="Eliminar"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/txt_content"
            app:layout_constraintVertical_chainStyle="spread" />
    
    </android.support.constraint.ConstraintLayout>

</ScrollView>

Scroll Topenter image description here

Scroll Bottomenter image description here

#92 Best answer 2 of Android - how to make a scrollable constraintlayout?(Score: 77)

Created: 2018-01-17 Last updated: 2018-10-05

There is a type of constraint which breaks the scroll function:

Just make sure you are not using this constraint on any view when wanting your ConstraintLayout to be scrollable with ScrollView :

app:layout_constraintBottom_toBottomOf=“parent”

If you remove these your scroll should work.

Explanation:

Setting the height of the child to match that of a ScrollView parent is contradictory to what the component is meant to do. What we want most of the time is for some dynamic sized content to be scrollable when it is larger than a screen/frame; matching the height with the parent ScrollView would force all the content to be displayed into a fixed frame (the height of the parent) hence invalidating any scrolling functionality.

This also happens when regular direct child components are set to layout_height="match_parent".

If you want the child of the ScrollView to match the height of the parent when there is not enough content, simply set android:fillViewport to true for the ScrollView.

See also original question in stackoverflow

#93: Border in shape XML (Score: 168)

Created: 2011-07-14 Last updated: 2021-04-01

Tags: android, android-layout, border, shapes, stroke

I am trying to make a drawable to use for a button. I would like it to have this coloring, with a 2px border around it.

Everything works just fine except I cannot get the border to show up…

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >
	 
    <gradient android:startColor="@color/bar_clicked_dark"
        android:endColor="@color/bar_clicked_light"
        android:angle="90"/>
        
    <corners android:bottomLeftRadius="0dp"
        android:topLeftRadius="15dp"
        android:bottomRightRadius="15dp"
        android:topRightRadius="0dp" />
		
    <stroke android:width="2dp" 
        color="#ff00ffff" />
		
</shape>

#93 Best answer 1 of Border in shape XML (Score: 301)

Created: 2011-07-14 Last updated: 2019-06-17

It looks like you forgot the prefix on the color attribute. Try

 <stroke android:width="2dp" android:color="#ff00ffff"/>

#93 Best answer 2 of Border in shape XML(Score: 86)

Created: 2015-04-16 Last updated: 2019-03-11

If you want make a border in a shape xml. You need to use:

For the external border,you need to use:

<stroke/>

For the internal background,you need to use:

<solid/>

If you want to set corners,you need to use:

<corners/>

If you want a padding betwen border and the internal elements,you need to use:

<padding/>

Here is a shape xml example using the above items. It works for me

<shape xmlns:android="http://schemas.android.com/apk/res/android"> 
  <stroke android:width="2dp" android:color="#D0CFCC" /> 
  <solid android:color="#F8F7F5" /> 
  <corners android:radius="10dp" />
  <padding android:left="2dp" android:top="2dp" android:right="2dp" android:bottom="2dp" />
</shape>

See also original question in stackoverflow

#94: How to dismiss the dialog with click on outside of the dialog? (Score: 165)

Created: 2011-12-05 Last updated: 2013-02-19

Tags: android, android-layout, android-emulator, dialog, android-dialog

I have implemented a custom dialog for my application. I want to implement that when the user clicks outside the dialog, the dialog will be dismissed. What do I have to do for this?

#94 Best answer 1 of How to dismiss the dialog with click on outside of the dialog? (Score: 369)

Created: 2011-12-05 Last updated: 2011-12-05

You can use dialog.setCanceledOnTouchOutside(true); which will close the dialog if you touch outside of the dialog.

Something like,

  Dialog dialog = new Dialog(context)
  dialog.setCanceledOnTouchOutside(true);

Or if your Dialog in non-model then,

1 - Set the flag-FLAG_NOT_TOUCH_MODAL for your dialog’s window attribute

Window window = this.getWindow();
window.setFlags(WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL,
WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL);

2 - Add another flag to windows properties,, FLAG_WATCH_OUTSIDE_TOUCH - this one is for dialog to receive touch event outside its visible region.

3 - Override onTouchEvent() of dialog and check for action type. if the action type is ‘MotionEvent.ACTION_OUTSIDE’ means, user is interacting outside the dialog region. So in this case, you can dimiss your dialog or decide what you wanted to perform. view plainprint?

public boolean onTouchEvent(MotionEvent event)  
{  
   
       if(event.getAction() == MotionEvent.ACTION_OUTSIDE){  
        System.out.println("TOuch outside the dialog ******************** ");  
               this.dismiss();  
       }  
       return false;  
}  

For more info look at How to dismiss a custom dialog based on touch points? and How to dismiss your non-modal dialog, when touched outside dialog region

#94 Best answer 2 of How to dismiss the dialog with click on outside of the dialog?(Score: 20)

Created: 2013-06-18

Simply use

dialog.setCanceledOnTouchOutside(true);

See also original question in stackoverflow

#95: Preview layout with merge root tag in Intellij IDEA/Android Studio (Score: 165)

Created: 2013-06-25 Last updated: 2016-09-20

Tags: android, android-layout, android-studio, intellij-idea, android-tools-namespace

Let’s imagine we are developing compound component based on LinearLayout. So, we create class like this:

public class SomeView extends LinearLayout {
    public SomeView(Context context, AttributeSet attrs) {
        super(context, attrs);

        setOrientation(LinearLayout.VERTICAL);
        View.inflate(context, R.layout.somelayout, this);
    }
}

If we’ll use LinearLayout as a root of somelayout.xml, we’ll have extra view level, so we use merge tag:

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Some text"
        android:textSize="20sp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Some other text"/>
</merge>

But in Preview tab in IDE merge always acts as FrameLayout, and we’ll see something like that: Preview with merge

(It is Android Studio, Intellij IDEA is just the same, about Eclipse I don’t know)

Preview speed up developing layouts a lot, it’s sad lose such a great help even for some layouts. May be there is a way to specify, how Preview should interpret merge tag in particular layout?

#95 Best answer 1 of Preview layout with merge root tag in Intellij IDEA/Android Studio (Score: 375)

Created: 2016-09-16 Last updated: 2016-09-29

There is a new parentTag tools attribute (added in Android Studio 2.2) that you can use to specify the layout type for a merge tag, which will make the layout render correctly in the layout editor preview.

So using your example:

<merge xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:parentTag="LinearLayout"
    tools:orientation="horizontal">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Some text"
        android:textSize="20sp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Some other text"/>
</merge>

Note: Both android:layout_width and android:layout_height must be specified in order for the layout to display properly in the editor.

#95 Best answer 2 of Preview layout with merge root tag in Intellij IDEA/Android Studio(Score: 66)

Created: 2014-05-09 Last updated: 2016-12-09

Edit: Outdated answer. See answer by starkej2.


Android Studio 0.5.8 added support for tools:showIn. By using it it is possible to preview < merge > layouts.

http://tools.android.com/recent/androidstudio058released

layout/layout_merge.xml with tools:showIn:

<merge xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:custom="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   tools:showIn="@layout/simple_relativelayout">

......

</merge>

layout/simple_relativelayout.xml with include:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <include layout="@layout/layout_merge"/>

</RelativeLayout>

See also original question in stackoverflow

#96: What is android:weightSum in android, and how does it work? (Score: 165)

Created: 2011-09-17 Last updated: 2016-03-19

Tags: android, android-layout, android-layout-weight

I want to know: What is android:weightSum and layout weight, and how do they work?

#96 Best answer 1 of What is android:weightSum in android, and how does it work? (Score: 178)

Created: 2012-10-08

Adding on to superM’s and Jeff’s answer,

If there are 2 views in the LinearLayout, the first with a layout_weight of 1, the second with a layout_weight of 2 and no weightSum is specified, by default, the weightSum is calculated to be 3 (sum of the weights of the children) and the first view takes 1/3 of the space while the second takes 2/3.

However, if we were to specify the weightSum as 5, the first would take 1/5th of the space while the second would take 2/5th. So a total of 3/5th of the space would be occupied by the layout keeping the rest empty.

#96 Best answer 2 of What is android:weightSum in android, and how does it work?(Score: 134)

Created: 2011-09-17 Last updated: 2017-03-16

Per documentation, android:weightSum defines the maximum weight sum, and is calculated as the sum of the layout_weight of all the children if not specified explicitly.

Let’s consider an example with a LinearLayout with horizontal orientation and 3 ImageViews inside it. Now we want these ImageViews always to take equal space. To acheive this, you can set the layout_weight of each ImageView to 1 and the weightSum will be calculated to be equal to 3 as shown in the comment.

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    <!-- android:weightSum="3" -->
    android:orientation="horizontal"
    android:layout_gravity="center">

   <ImageView
       android:layout_height="wrap_content"       
       android:layout_weight="1"
       android:layout_width="0dp"/>
  .....

weightSum is useful for having the layout rendered correctly for any device, which will not happen if you set width and height directly.

See also original question in stackoverflow

#97: Why are nested weights bad for performance? Alternatives? (Score: 165)

Created: 2012-02-24 Last updated: 2012-03-02

Tags: android, android-layout, performance

I have written a couple layout files where I used the layout_weight attribute to create a ratio between different views.

At some point, I start getting lint warnings about nested weights.

So, I wonder why are nested weights bad for performance, and if there is a more efficient way to create a constant ratio between view dimensions that could be used for different screen sizes and that doesn’t need to specify a lot of dimension dpi values throught several layout files (for different screen sizes, I mean).

Thank you!

#97 Best answer 1 of Why are nested weights bad for performance? Alternatives? (Score: 144)

Created: 2012-02-24 Last updated: 2018-10-01

Nested weights are bad for performance because:

Layout weights require a widget to be measured twice. When a LinearLayout with non-zero weights is nested inside another LinearLayout with non-zero weights, then the number of measurements increase exponentially.

It’s better to use RelativeLayouts and adjust your view according to the places of other views without using specific dpi values.

#97 Best answer 2 of Why are nested weights bad for performance? Alternatives?(Score: 69)

Created: 2015-09-06 Last updated: 2018-03-09

Update: As we know the percent support library is deprecated from API level 26. ConstraintLayout is the new way to achieve the same flat xml structure.

Updated Github Project

Updated Samples:

<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/fifty_thirty"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="#ffff8800"
        android:gravity="center"
        android:text="@string/fifty_fifty_text"
        android:textColor="@android:color/white"
        app:layout_constraintHeight_default="percent"
        app:layout_constraintHeight_percent="0.5"
        android:textSize="25sp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintWidth_default="percent"
        app:layout_constraintWidth_percent="0.5" />

    <TextView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="#ffff5566"
        android:gravity="center"
        android:text="@string/fifty_fifty_text"
        android:textColor="@android:color/white"
        android:textSize="25sp"
        app:layout_constraintHeight_default="percent"
        app:layout_constraintHeight_percent="0.5"
        app:layout_constraintLeft_toRightOf="@id/fifty_thirty"
        app:layout_constraintTop_toBottomOf="@id/fifty_thirty"
        app:layout_constraintWidth_default="percent"
        app:layout_constraintWidth_percent="0.5" />

</android.support.constraint.ConstraintLayout>

Update: Great news android percent support library solves our problem of performance and nested messy weighted LinearLayout

compile 'com.android.support:percent:23.0.0'

Demo HERE

Consider this simple layout to demonstrate the same.

percent support libray demo

<android.support.percent.PercentRelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/fifty_huntv"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="#ff7acfff"
        android:text="20% - 50%"
        android:textColor="@android:color/white"
        app:layout_heightPercent="20%"
        app:layout_widthPercent="50%" />
    <TextView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_toRightOf="@id/fifty_huntv"
        android:background="#ffff5566"
        android:text="80%-50%"
        app:layout_heightPercent="80%"
        app:layout_widthPercent="50%"
        />

</android.support.percent.PercentRelativeLayout>

Avoided performance degrader nested LinearLayout with weights.Really awesome!!!.

See also original question in stackoverflow

#98: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference (Score: 162)

Created: 2015-02-19 Last updated: 2020-07-12

Tags: android, android-layout, android-fragments, android-listview

I’m trying to put together a shopping list app, based on input fields, ArrayList, and ListView. The app will be based on Fragments. However, I have encountered a problem and I do not know how to solve it.

I looked around on both Google and StackOverflow and I have found some information. However, I have not got it to work. Now I hope that I can get help with my code.

I’m relatively inexperienced in Android development.

Main.java

import java.util.ArrayList;

import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
import android.view.MenuItem;

public class Main extends FragmentActivity {
	
    ArrayList<Detail> items = new ArrayList<Detail>();
    FragmentManager FM;
    FragmentTransaction FT;
    Input input = new Input();
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
		
        replaceFragment(R.id.container, input);
    }

	
    public void replaceFragment(int container, Fragment fragment){
        FM = getFragmentManager();
        FT = FM.beginTransaction();
		
        FT.replace(container, fragment);
        FT.commit();
    }
	
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

ListAdapter.java

public class ListAdapter extends BaseAdapter {

    Context context;
    ArrayList<Detail> items;
	
    public ListAdapter(Context context, ArrayList<Detail> items) {
        this.context = context;
        this.items = items;
    }
	
    @Override
    public int getCount() {
        return items.size();
    }

    @Override
    public Object getItem(int position) {
        return items.get(position);
    }

    @Override
    public long getItemId(int position) {
        return items.indexOf(getItem(position));
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
		
        if(convertView == null){
            LayoutInflater lInflater = (LayoutInflater)context.getSystemService(
                    Activity.LAYOUT_INFLATER_SERVICE);
			
            convertView = lInflater.inflate(R.layout.list_row, null);		
        }
		
        TextView title = (TextView)convertView.findViewById(R.id.itemTitle);
        CheckBox done = (CheckBox)convertView.findViewById(R.id.itemDone);
		
		
        Detail detail_position = items.get(position);
		
        title.setText(detail_position.getTitle());
        done.setChecked(detail_position.isDone());
		
        return null;
    }
}

List.java

import java.util.ArrayList;

import android.app.ListFragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;

public class List extends ListFragment implements OnItemClickListener{

    ArrayList<Detail> items;
    ListAdapter adapter;
    private onClickListener OCL;

    interface onClickListener{
        public void onItemClick(int id);
    }

    public List(ArrayList<Detail> items) {
        this.items = items;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        View root = inflater.inflate(R.layout.list_layout, container, false);
        return root;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        if(items != null){
            adapter = new ListAdapter(getActivity(), items);
            setListAdapter(adapter);
            getListView().setOnItemClickListener(this);
        }

    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {

        if(OCL != null){
            OCL.onItemClick(position);
        }		
    }
}

list_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ListView
        android:id="@+id/android:list"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </ListView>
</LinearLayout>

list_row

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:padding="10dp" >
    <TextView
        android:id="@+id/itemTitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0.96"
        android:text="Medium Text"
        android:textAppearance="?android:attr/textAppearanceMedium" />
    <CheckBox
        android:id="@+id/itemDone"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Done" />
</LinearLayout>

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.com.hermods.lab2_2.Main" >
</RelativeLayout>

Log

02-19 09:10:47.421: E/AndroidRuntime(12745): Process: com.example.com.hermods.lab2_2, PID: 12745
02-19 09:10:47.421: E/AndroidRuntime(12745): java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.AbsListView.obtainView(AbsListView.java:2360)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.makeAndAddView(ListView.java:1864)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.fillDown(ListView.java:698)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.fillFromTop(ListView.java:759)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.layoutChildren(ListView.java:1673)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.AbsListView.onLayout(AbsListView.java:2148)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1076)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2072)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1829)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer.doCallbacks(Choreographer.java:580)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer.doFrame(Choreographer.java:550)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.os.Handler.handleCallback(Handler.java:739)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.os.Handler.dispatchMessage(Handler.java:95)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.os.Looper.loop(Looper.java:135)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.app.ActivityThread.main(ActivityThread.java:5221)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at java.lang.reflect.Method.invoke(Native Method)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at java.lang.reflect.Method.invoke(Method.java:372)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

#98 Best answer 1 of java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference (Score: 405)

Created: 2015-02-19 Last updated: 2016-06-29

In your public View getView method change return null; to return convertView;.

#98 Best answer 2 of java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference(Score: 15)

Created: 2015-12-19 Last updated: 2018-05-16

#use return convertView;

Code:

public View getView(final int position, View convertView, ViewGroup parent) {
   
    //convertView = null;

    if (convertView == null) {

        LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        convertView = mInflater.inflate(R.layout.list_item, null);     

        TextView tv = (TextView) convertView.findViewById(R.id.name);
        Button rm_btn = (Button) convertView.findViewById(R.id.rm_btn);

        Model m = modelList.get(position);
        tv.setText(m.getName());

        // click listener for remove button  คลิกลบปุ่ม
        rm_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                modelList.remove(position);
                notifyDataSetChanged();
            }
        });
    }

    ///#use    return convertView;
    return convertView;
}

See also original question in stackoverflow

#99: ListView inside ScrollView is not scrolling on Android (Score: 160)

Created: 2011-06-02 Last updated: 2014-06-16

Tags: android, listview, android-layout, scrollview

I am having trouble with a scrolling ListView inside a ScrollView. I have an Activity which has some EditTexts in the top part and then a tab host with two tabs which have one ListView each. When the EditText views are focused, the soft keyboard comes up and as I have a ScrollView, the content is scrollable. But the problem comes when there are more items in ListViews (ones in tabs), I am not able to scroll the ListView, even if there are more items.

The following is the layout XML:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="?backgroundImage"
    android:orientation="vertical">

  <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="50dip"
        android:layout_alignParentBottom="true"
        android:layout_margin="10dip"
        android:id="@+id/buttons">
    <Button
            android:text="Save"
            android:layout_margin="2dip"
            android:textSize="20dip"
            android:id="@+id/btnSaveorUpdate"
            android:layout_height="wrap_content"
            android:layout_width="145dip"></Button>
    <Button
            android:text="Cancel"
            android:layout_margin="2dip"
            android:textSize="20dip"
            android:id="@+id/btnCancelorDelete"
            android:layout_height="wrap_content"
            android:layout_width="145dip"></Button>
  </LinearLayout>
  <ScrollView
        android:layout_above="@id/buttons"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:fillViewport="true"
        android:layout_margin="10dip">
    <LinearLayout
            android:orientation="vertical"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_margin="10dip">
      <TextView
                android:text="Bill details"
                android:textColor="?textColorDark"
                android:layout_alignParentTop="true"
                android:id="@+id/txtEnterDetails"
                android:textSize="25dip"
                android:textStyle="bold"
                android:layout_height="wrap_content"
                android:layout_width="fill_parent"
                android:layout_marginBottom="2dip"></TextView>
      <LinearLayout
                android:focusable="true"
                android:focusableInTouchMode="true"
                android:layout_width="0dip"
                android:layout_height="0dip" />
      <EditText
                android:layout_width="fill_parent"
                android:hint="Enter data"
                android:inputType="numberDecimal"
                android:id="@+id/txtSample"
                android:textSize="@dimen/editText"
                android:layout_height="@dimen/editTextHeight"
                android:text=""></EditText>
      <EditText
                android:layout_width="fill_parent"
                android:id="@+id/txtDescription"
                android:hint="Enter description"
                android:textSize="@dimen/editText"
                android:layout_height="@dimen/editTextHeight"
                android:inputType="text"
                android:text=""></EditText>
      <EditText
                android:layout_width="fill_parent"
                android:id="@+id/txtComment"
                android:hint="Enter comment (if any)"
                android:textSize="@dimen/editText"
                android:layout_height="@dimen/editTextHeight"
                android:inputType="text"
                android:text=""></EditText>
      <LinearLayout
                android:orientation="horizontal"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content">
        <TextView
                    android:id="@+id/txtDate"
                    android:layout_width="wrap_content"
                    android:text=""
                    android:textSize="20dip"
                    android:textColor="?textColorDark"
                    android:layout_marginLeft="10dip"
                    android:layout_height="@dimen/editTextHeight"
                    android:layout_gravity="center_vertical" />
        <Button
                    android:id="@+id/btnPickDate"
                    android:layout_width="wrap_content"
                    android:layout_height="@dimen/editTextHeight"
                    android:text="Select date"
                    android:layout_margin="2dip"
                    android:textSize="15dip"
                    android:layout_gravity="center_vertical" />
      </LinearLayout>
      <TabHost
                android:id="@+id/tabhost"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent">
        <LinearLayout
                    android:id="@+id/linearLayout1"
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"
                    android:orientation="vertical">
          <TabWidget
                        android:layout_width="fill_parent"
                        android:layout_height="wrap_content"
                        android:id="@android:id/tabs"></TabWidget>
          <FrameLayout
                        android:layout_width="fill_parent"
                        android:layout_height="fill_parent"
                        android:id="@android:id/tabcontent">
            <ScrollView
                            android:layout_above="@id/buttons"
                            android:layout_width="fill_parent"
                            android:layout_height="fill_parent"
                            android:fillViewport="true"
                            android:id="@+id/tab1">
              <LinearLayout
                                android:layout_width="fill_parent"
                                android:layout_height="wrap_content"
                                android:orientation="vertical">
                <TableLayout
                                    android:layout_height="wrap_content"
                                    android:layout_width="fill_parent">
                  <TableRow
                                        android:id="@+id/tableRow1"
                                        android:layout_marginLeft="2dip"
                                        android:layout_marginRight="5dip"
                                        android:layout_width="fill_parent"
                                        android:layout_height="wrap_content">
                    <LinearLayout
                                            android:layout_width="fill_parent"
                                            android:layout_height="wrap_content"
                                            android:orientation="horizontal">
                      <ImageView
                                                android:src="@drawable/ic_menu_invite"
                                                android:layout_width="40dip"
                                                android:layout_height="40dip"
                                                android:layout_gravity="center_vertical"></ImageView>
                      <TextView
                                                android:text="Add friend"
                                                android:layout_height="wrap_content"
                                                android:layout_width="fill_parent"
                                                android:layout_centerVertical="true"
                                                android:textColor="?textColorDark"
                                                android:textSize="@dimen/editText"
                                                android:layout_gravity="center_vertical" />
                    </LinearLayout>
                  </TableRow>
                  <TableRow
                                        android:layout_width="fill_parent"
                                        android:layout_height="wrap_content"
                                        android:layout_marginLeft="5dip"
                                        android:layout_marginRight="5dip">
                    <TextView
                                            android:id="@+id/txtData1"
                                            android:layout_width="170dip"
                                            android:layout_height="wrap_content"
                                            android:text="Data"
                                            android:textSize="14dip"
                                            android:textStyle="bold"
                                            android:textColor="#000000">
                    </TextView>
                    <TextView
                                            android:id="@+id/txtData2"
                                            android:layout_width="wrap_content"
                                            android:layout_height="wrap_content"
                                            android:text="Sample"
                                            android:textSize="13dip"
                                            android:textColor="#000000"></TextView>

                  </TableRow>
                </TableLayout>
                <ListView
                                    android:cacheColorHint="#00000000"
                                    android:id="@+id/ListView01"
                                    android:layout_height="wrap_content"
                                    android:layout_width="fill_parent" />
              </LinearLayout>
            </ScrollView>
            <LinearLayout
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:gravity="center_horizontal"
                            android:id="@+id/tab2"
                            android:orientation="vertical">
              <TableLayout
                                android:layout_height="wrap_content"
                                android:layout_width="fill_parent">
                <TableRow
                                    android:id="@+id/tableRow2"
                                    android:layout_marginLeft="2dip"
                                    android:layout_marginRight="5dip"
                                    android:layout_width="fill_parent"
                                    android:layout_height="wrap_content">
                  <LinearLayout
                                        android:layout_width="fill_parent"
                                        android:layout_height="wrap_content"
                                        android:orientation="horizontal">
                    <ImageView
                                            android:src="@drawable/ic_menu_invite"
                                            android:layout_width="40dip"
                                            android:layout_height="40dip"
                                            android:layout_gravity="center_vertical"></ImageView>
                    <TextView
                                            android:text="Sample"
                                            android:layout_height="wrap_content"
                                            android:layout_width="fill_parent"
                                            android:layout_centerVertical="true"
                                            android:textColor="?textColorDark"
                                            android:textSize="@dimen/editText"
                                            android:layout_gravity="center_vertical" />
                  </LinearLayout>
                </TableRow>
                <TableRow
                                    android:layout_width="fill_parent"
                                    android:layout_height="wrap_content"
                                    android:layout_marginLeft="5dip"
                                    android:layout_marginRight="5dip">
                  <TextView
                                        android:id="@+id/txtUser1"
                                        android:layout_width="170dip"
                                        android:layout_height="wrap_content"
                                        android:text="User"
                                        android:textSize="14dip"
                                        android:textStyle="bold"
                                        android:textColor="#000000">
                  </TextView>
                  <TextView
                                        android:id="@+id/txtUserData"
                                        android:layout_width="wrap_content"
                                        android:layout_height="wrap_content"
                                        android:text="UserData"
                                        android:textSize="13dip"
                                        android:textColor="#000000"></TextView>
                </TableRow>
              </TableLayout>

              <ListView
                                android:cacheColorHint="#00000000"
                                android:id="@+id/ListView02"
                                android:layout_height="wrap_content"
                                android:layout_width="fill_parent" />

            </LinearLayout>


          </FrameLayout>
        </LinearLayout>
      </TabHost>
    </LinearLayout>
  </ScrollView>
</RelativeLayout>

Please can anyone tell me what the problem is here? I have another post on the ListView inside ScrollView problem, but they were of no use in my case.

#99 Best answer 1 of ListView inside ScrollView is not scrolling on Android (Score: 309)

Created: 2013-01-29 Last updated: 2014-06-16

I found a solution that works excellently and can scroll the ListView without problems:

ListView lv = (ListView)findViewById(R.id.myListView);  // your listview inside scrollview
lv.setOnTouchListener(new ListView.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int action = event.getAction();
            switch (action) {
            case MotionEvent.ACTION_DOWN:
                // Disallow ScrollView to intercept touch events.
                v.getParent().requestDisallowInterceptTouchEvent(true);
                break;

            case MotionEvent.ACTION_UP:
                // Allow ScrollView to intercept touch events.
                v.getParent().requestDisallowInterceptTouchEvent(false);
                break;
            }

            // Handle ListView touch events.
            v.onTouchEvent(event);
            return true;
        }
    });

What this does is disable the TouchEvents on the ScrollView and make the ListView intercept them. It is simple and works all the time.

#99 Best answer 2 of ListView inside ScrollView is not scrolling on Android(Score: 183)

Created: 2011-06-02 Last updated: 2015-08-24

You shouldn’t put a ListView inside a ScrollView because the ListView class implements its own scrolling and it just doesn’t receive gestures because they all are handled by the parent ScrollView. I strongly recommend you to simplify your layout somehow. For example you can add views you want to be scrolled to the ListView as headers or footers.

UPDATE:

Starting from API Level 21 (Lollipop) nested scroll containers are officially supported by Android SDK. There’re a bunch of methods in View and ViewGroup classes which provide this functionality. To make nested scrolling work on the Lollipop you have to enable it for a child scroll view by adding android:nestedScrollingEnabled="true" to its XML declaration or by explicitly calling setNestedScrollingEnabled(true).

If you want to make nested scrolling work on pre-Lollipop devices, which you probably do, you have to use corresponding utility classes from the Support library. First you have to replace you ScrollView with NestedScrollView. The latter implements both NestedScrollingParent and NestedScrollingChild so it can be used as a parent or a child scroll container.

But ListView doesn’t support nested scrolling, therefore you need to subclass it and implement NestedScrollingChild. Fortunately, the Support library provides NestedScrollingChildHelper class, so you just have to create an instance of this class and call its methods from the corresponding methods of your view class.

See also original question in stackoverflow

#100: One Activity and all other Fragments (Score: 158)

Created: 2012-08-28 Last updated: 2012-09-06

Tags: android, android-layout, android-activity, android-fragments, android-lifecycle

I am thinking of implementing one screen with Activity and all other sreens with Fragments and managing all the fragments thru the activity.

Is it a good idea? and my answer is NO but still I want to know more clearly about this thought.

What are the pros and cons of the idea?

Note:

Please don’t give me the link for fragment and activity.

EDIT:

Here is something over Fragments and activity:

Pros:

  1. Fragments are meant to be used with activities as a sub activity.
  2. Fragments are not the replacement for activities.
  3. Fragments are meant for reusability(Need to know in what way reusability can be achieved.).
  4. Fragments are the best way to write code to support both tablets and phones.

Cons:

  1. We need to implement the interface to get the data from fragments.
  2. For dialog we have to go a long way to show it.

Why should we use fragments if we are not considering tablets? What is the starting time difference between activity and fragment?

#100 Best answer 1 of One Activity and all other Fragments (Score: 95)

Created: 2012-08-31 Last updated: 2018-05-02

It depends on the app you are creating. I’ve created several apps using both approaches and can’t say one way is always better than the other. The latest app I created I used the single Activity approach and a Facebook style navigation. When selecting items from the navigation list I update a single Fragment container to display that section.

That said, having a single Activity also introduces a lot of complexities. Let’s say you have an edit form, and for some of the items the user needs to select, or create, requires them to go to a new screen. With activities we’d just call the new screen with startActivityForResult but with Fragments there is no such thing so you end up storing the value on the Activity and having the main edit fragment check the Activity to see if data has been selected and should be displayed to the user.

What Aravind says about being stuck to a single Activity type is also true but not really that limiting. Your activity would be a FragmentActivity and as long as you don’t need a MapView then there are no real limitations. If you do want to display maps though, it can be done, but you’ll need to either modify the Android Compatibility Library to have FragmentActivity extend MapActivity or use the the publicly available android-support-v4-googlemaps.

Ultimately most the devs I know that went the one Activity route have gone back to multiple Activities to simplify their code. UI wise, on a tablet, you are some times stuck using a single Activity just to achieve what ever crazy interaction your designers come up with :)

– EDIT –

Google has finally released MapFragment to the compatibility library so you no longer have to use the android-support-v4-googlemaps hack. Read about the update here: Google Maps Android API v2

– EDIT 2 –

I just read this great post about the modern (2017) state of fragments and remembered this old answer. Thought I would share: Fragments: The Solution to All of Android’s Problems

#100 Best answer 2 of One Activity and all other Fragments(Score: 85)

Created: 2013-08-08 Last updated: 2015-07-04

I’m about to finish a project(5 months in development), that has 1 activity, and 17 fragments, all full screen. This is my second fragment based project(previous was 4 months).

Pros

  • The main activity is 700 lines of code, just nicely managing the order of the fragments navigation.
  • Each fragment is nicely separated into it’s own class, and is relatively small (~couple hundred lines of ui stuff).
  • Management can say, “hey, how about we switch the order of those screens”, and I can do it very easily, as those fragments don’t depend on each other, they all communicate through the activity. I don’t have to dig through individual activities, to find where they call each other.
  • my app is very graphics heavy, and would never work as 1 screen 1 activity. All those sub activities in the memory, would make the app run out of memory all the time, so I would have to finish() all non visible activities, and make the same control logic for navigation, as I would do with fragments. Might as well do it with fragments just because of this.
  • if we ever do a tablet app, we will have an easier time re-factoring stuff, because everything is nicely separated already.

Cons

  • you have to learn, how to use fragments

See also original question in stackoverflow


Notes:
  1. This page use API to get the relevant data from stackoverflow community.
  2. Content license on this page is CC BY-SA 3.0.
  3. score = up votes - down votes.