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Most votes on android-layout questions 9

Most votes on android-layout questions 9. #81 Nested Recycler view height doesn't wrap its content #82 How do I create a ListView with rounded corners in Android? #83 How do I add a bullet symbol in TextView? #84 Android Spinner : Avoid onItemSelected calls during initialization #85 Toolbar overlapping below status bar #86 How to center the content inside a linear layout? #87 Vertical line using XML drawable #88 Why does LayoutInflater ignore the layout_width and layout_height layout parameters I've specified? #89 Flinging with RecyclerView + AppBarLayout #90 What is the 'app' Android XML namespace?

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#81: Nested Recycler view height doesn't wrap its content (Score: 179)

Created: 2014-10-30 Last updated: 2017-06-16

Tags: android, android-layout, android-studio, android-recyclerview, android-support-library

I have an application that manage collections of books (like playlists).

I want to display a list of collection with a vertical RecyclerView and inside each row, a list of book in an horizontal RecyclerView.

When i set the layout_height of the inner horizontal RecyclerView to 300dp, it is displayed correctly but when i set it to wrap_content, it doesn’t display anything. I need to use wrap_content because I want to be able to change the layout manager programmatically to switch between vertical and horizontal display.

enter image description here

Do you know what i’m doing wrong ?

My Fragment layout :

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="@color/white">

    <com.twibit.ui.view.CustomSwipeToRefreshLayout
        android:id="@+id/swipe_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <android.support.v7.widget.RecyclerView
                android:id="@+id/shelf_collection_listview"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:paddingTop="10dp"/>

        </LinearLayout>

    </com.twibit.ui.view.CustomSwipeToRefreshLayout>
</LinearLayout>

Collection element layout :

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:orientation="vertical">

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

        <!-- Simple Header -->

    </RelativeLayout>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="@string/empty_collection"
            android:id="@+id/empty_collection_tv"
            android:visibility="gone"
            android:gravity="center"/>

        <android.support.v7.widget.RecyclerView
            android:id="@+id/collection_book_listview"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/> <!-- android:layout_height="300dp" -->

    </FrameLayout>

</LinearLayout>

Book list item :

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="180dp"
              android:layout_height="220dp"
              android:layout_gravity="center">

        <ImageView
            android:id="@+id/shelf_item_cover"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:maxWidth="150dp"
            android:maxHeight="200dp"
            android:src="@drawable/placeholder"
            android:contentDescription="@string/cover"
            android:adjustViewBounds="true"
            android:background="@android:drawable/dialog_holo_light_frame"/>

</FrameLayout>

Here is my Collection Adapter :

private class CollectionsListAdapter extends RecyclerView.Adapter<CollectionsListAdapter.ViewHolder> {
    private final String TAG = CollectionsListAdapter.class.getSimpleName();
    private Context mContext;

    // Create the ViewHolder class to keep references to your views
    class ViewHolder extends RecyclerView.ViewHolder {

        private final TextView mHeaderTitleTextView;
        private final TextView mHeaderCountTextView;

        private final RecyclerView mHorizontalListView;
        private final TextView mEmptyTextView;

        public ViewHolder(View view) {
            super(view);

            mHeaderTitleTextView = (TextView) view.findViewById(R.id.collection_header_tv);
            mHeaderCountTextView = (TextView) view.findViewById(R.id.collection_header_count_tv);

            mHorizontalListView = (RecyclerView) view.findViewById(R.id.collection_book_listview);
            mEmptyTextView = (TextView) view.findViewById(R.id.empty_collection_tv);
        }
    }


    public CollectionsListAdapter(Context context) {
        mContext = context;
    }


    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int i) {
        Log.d(TAG, "CollectionsListAdapter.onCreateViewHolder(" + parent.getId() + ", " + i + ")");
        // Create a new view by inflating the row item xml.
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.shelf_collection, parent, false);

        // Set the view to the ViewHolder
        ViewHolder holder = new ViewHolder(v);

        holder.mHorizontalListView.setHasFixedSize(false);
        holder.mHorizontalListView.setHorizontalScrollBarEnabled(true);

        // use a linear layout manager
        LinearLayoutManager mLayoutManager = new LinearLayoutManager(mContext);
        mLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        holder.mHorizontalListView.setLayoutManager(mLayoutManager);

        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int i) {
        Log.d(TAG, "CollectionsListAdapter.onBindViewHolder(" + holder.getPosition() + ", " + i + ")");

        Collection collection = mCollectionList.get(i);
        Log.d(TAG, "Collection : " + collection.getLabel());

        holder.mHeaderTitleTextView.setText(collection.getLabel());
        holder.mHeaderCountTextView.setText("" + collection.getBooks().size());

        // Create an adapter if none exists
        if (!mBookListAdapterMap.containsKey(collection.getCollectionId())) {
            mBookListAdapterMap.put(collection.getCollectionId(), new BookListAdapter(getActivity(), collection));
        }

        holder.mHorizontalListView.setAdapter(mBookListAdapterMap.get(collection.getCollectionId()));

    }

    @Override
    public int getItemCount() {
        return mCollectionList.size();
    }
}

And finally, the Book adapter :

private class BookListAdapter extends RecyclerView.Adapter<BookListAdapter.ViewHolder> implements View.OnClickListener {
    private final String TAG = BookListAdapter.class.getSimpleName();

    // Create the ViewHolder class to keep references to your views
    class ViewHolder extends RecyclerView.ViewHolder {
        public ImageView mCoverImageView;

        public ViewHolder(View view) {
            super(view);
            mCoverImageView = (ImageView) view.findViewById(R.id.shelf_item_cover);
        }
    }

    @Override
    public void onClick(View v) {
        BookListAdapter.ViewHolder holder = (BookListAdapter.ViewHolder) v.getTag();
        int position = holder.getPosition();
        final Book book = mCollection.getBooks().get(position);

        // Click on cover image
        if (v.getId() == holder.mCoverImageView.getId()) {
            downloadOrOpenBook(book);
            return;
        }
    }

    private void downloadOrOpenBook(final Book book) {
        // do stuff
    }

    private Context mContext;
    private Collection mCollection;

    public BookListAdapter(Context context, Collection collection) {
        Log.d(TAG, "BookListAdapter(" + context + ", " + collection + ")");
        mCollection = collection;
        mContext = context;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int i) {
        Log.d(TAG, "onCreateViewHolder(" + parent.getId() + ", " + i + ")");
        // Create a new view by inflating the row item xml.
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.shelf_grid_item, parent, false);

        // Set the view to the ViewHolder
        ViewHolder holder = new ViewHolder(v);
        holder.mCoverImageView.setOnClickListener(BookListAdapter.this); // Download or Open

        holder.mCoverImageView.setTag(holder);

        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int i) {
        Log.d(TAG, "onBindViewHolder(" + holder.getPosition() + ", " + i + ")");

        Book book = mCollection.getBooks().get(i);

        ImageView imageView = holder.mCoverImageView;
        ImageLoader.getInstance().displayImage(book.getCoverUrl(), imageView);
    }

    @Override
    public int getItemCount() {
        return mCollection.getBooks().size();
    }
}

#81 Best answer 1 of Nested Recycler view height doesn't wrap its content (Score: 124)

Created: 2014-12-23 Last updated: 2014-12-23

@user2302510 solution works not as good as you may expected. Full workaround for both orientations and dynamically data changes is:

public class MyLinearLayoutManager extends LinearLayoutManager {

    public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout)    {
        super(context, orientation, reverseLayout);
    }

    private int[] mMeasuredDimension = new int[2];

    @Override
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                          int widthSpec, int heightSpec) {
        final int widthMode = View.MeasureSpec.getMode(widthSpec);
        final int heightMode = View.MeasureSpec.getMode(heightSpec);
        final int widthSize = View.MeasureSpec.getSize(widthSpec);
        final int heightSize = View.MeasureSpec.getSize(heightSpec);
        int width = 0;
        int height = 0;
        for (int i = 0; i < getItemCount(); i++) {
            measureScrapChild(recycler, i,
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    mMeasuredDimension);

            if (getOrientation() == HORIZONTAL) {
                width = width + mMeasuredDimension[0];
                if (i == 0) {
                    height = mMeasuredDimension[1];
                }
            } else {
                height = height + mMeasuredDimension[1];
                if (i == 0) {
                    width = mMeasuredDimension[0];
                }
            }
        }
        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        setMeasuredDimension(width, height);
    }

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        View view = recycler.getViewForPosition(position);
        if (view != null) {
            RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
            int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight(), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom(), p.height);
            view.measure(childWidthSpec, childHeightSpec);
            measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
            measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
            recycler.recycleView(view);
        }
    }
}

#81 Best answer 2 of Nested Recycler view height doesn't wrap its content(Score: 46)

Created: 2016-02-25 Last updated: 2016-03-17

Update

Many issues relating to this feature in version 23.2.0 have been fixed in 23.2.1, update to that instead.

With the release of Support Library version 23.2, RecyclerView now supports that!

Update build.gradle to:

compile 'com.android.support:recyclerview-v7:23.2.1'

or any version beyond that.

This release brings an exciting new feature to the LayoutManager API: auto-measurement! This allows a RecyclerView to size itself based on the size of its contents. This means that previously unavailable scenarios, such as using WRAP_CONTENT for a dimension of the RecyclerView, are now possible. You’ll find all built in LayoutManagers now support auto-measurement.

This can be disabled via setAutoMeasurementEnabled() if need be. Check in detail here.

See also original question in stackoverflow

#82: How do I create a ListView with rounded corners in Android? (Score: 177)

Created: 2009-11-05 Last updated: 2014-12-29

Tags: android, android-layout, android-listview

How do I create a ListView with rounded corners in Android?

#82 Best answer 1 of How do I create a ListView with rounded corners in Android? (Score: 376)

Created: 2009-11-05 Last updated: 2013-02-21

Here is one way of doing it (Thanks to Android Documentation though!):

Add the following into a file (say customshape.xml) and then place it in (res/drawable/customshape.xml)

<?xml version="1.0" encoding="UTF-8"?> 
<shape xmlns:android="http://schemas.android.com/apk/res/android" 
     android:shape="rectangle"> 
     <gradient 
         android:startColor="#SomeGradientBeginColor"
         android:endColor="#SomeGradientEndColor" 
         android:angle="270"/> 
    
    <corners 
         android:bottomRightRadius="7dp" 
         android:bottomLeftRadius="7dp" 
         android:topLeftRadius="7dp" 
         android:topRightRadius="7dp"/> 
</shape> 

Once you are done with creating this file, just set the background in one of the following ways:

Through Code: listView.setBackgroundResource(R.drawable.customshape);

Through XML, just add the following attribute to the container (ex: LinearLayout or to any fields):

android:background="@drawable/customshape"

Hope someone finds it useful…

#82 Best answer 2 of How do I create a ListView with rounded corners in Android?(Score: 56)

Created: 2011-04-03

Although that did work, it took out the entire background colour as well. I was looking for a way to do just the border and just replace that XML layout code with this one and I was good to go!

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <stroke android:width="4dp" android:color="#FF00FF00" />
    <padding android:left="7dp" android:top="7dp"
            android:right="7dp" android:bottom="7dp" />
    <corners android:radius="4dp" />
</shape> 

See also original question in stackoverflow

#83: How do I add a bullet symbol in TextView? (Score: 176)

Created: 2010-08-07 Last updated: 2014-03-09

Tags: android, android-layout, special-characters, textview

I have a TextView and I want to add a bullet symbol in my text through XML. Is it possible?

#83 Best answer 1 of How do I add a bullet symbol in TextView? (Score: 392)

Created: 2010-08-07 Last updated: 2015-12-29

You have to use the right character encoding to accomplish this effect. You could try with &#8226;


Update

Just to clarify: use `setText("\u2022 Bullet");` to add the bullet programmatically. `0x2022 = 8226`

#83 Best answer 2 of How do I add a bullet symbol in TextView?(Score: 65)

Created: 2013-07-29 Last updated: 2016-03-04

This worked for me:

<string name="text_with_bullet">Text with a \u2022</string>

See also original question in stackoverflow

#84: Android Spinner : Avoid onItemSelected calls during initialization (Score: 176)

Created: 2012-11-15 Last updated: 2019-06-12

Tags: android, android-layout, android-spinner

I created an Android application with a Spinner and a TextView. I want to display the selected item from the Spinner’s drop down list in the TextView. I implemented the Spinner in the onCreate method so when I’m running the program, it shows a value in the TextView (before selecting an item from the drop down list).

I want to show the value in the TextView only after selecting an item from the drop down list. How do I do this?

Here is my code:

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;

public class GPACal01Activity extends Activity implements OnItemSelectedListener {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Spinner spinner = (Spinner) findViewById(R.id.noOfSubjects);

        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,R.array.noofsubjects_array, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);
    }

    public void onItemSelected(AdapterView<?> parent, View arg1, int pos,long id) {
        TextView textView = (TextView) findViewById(R.id.textView1);
        String str = (String) parent.getItemAtPosition(pos);
        textView.setText(str);
    }

    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }
}

#84 Best answer 1 of Android Spinner : Avoid onItemSelected calls during initialization (Score: 192)

Created: 2012-11-15 Last updated: 2017-05-23

spinner.setOnItemSelectedListener(this); // Will call onItemSelected() Listener.

So first time handle this with any Integer value

Example: Initially Take int check = 0;

public void onItemSelected(AdapterView<?> parent, View arg1, int pos,long id) {
   if(++check > 1) {
      TextView textView = (TextView) findViewById(R.id.textView1);
      String str = (String) parent.getItemAtPosition(pos);
      textView.setText(str);
   }
}

You can do it with boolean value and also by checking current and previous positions. See here

#84 Best answer 2 of Android Spinner : Avoid onItemSelected calls during initialization(Score: 147)

Created: 2016-06-01 Last updated: 2018-10-08

Just put this line before set OnItemSelectedListener

spinner.setSelection(0,false)

See also original question in stackoverflow

#85: Toolbar overlapping below status bar (Score: 176)

Created: 2015-04-20 Last updated: 2020-08-28

Tags: android, xml, android-layout, material-design, material-components-android

I want to have appcompat v21 toolbar in my activity. But the toolbar I’m implementing is overlapping below status bar. How can I fix it?

overlapping toolbar

Here is the activity layout xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar" />

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

Toolbar view:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="?attr/actionBarSize"
    android:background="?attr/colorPrimary" />

Theme style:

<style name="AppTheme" parent="MaterialNavigationDrawerTheme.Light.DarkActionBar">
    <item name="colorPrimary">@color/primary</item>
    <item name="colorPrimaryDark">@color/primary_dark</item>
    <item name="colorAccent">@color/accent</item>
</style>

#85 Best answer 1 of Toolbar overlapping below status bar (Score: 284)

Created: 2015-04-20 Last updated: 2015-04-20

Use android:fitsSystemWindows="true" in the root view of your layout (LinearLayout in your case). And android:fitsSystemWindows is an

internal attribute to adjust view layout based on system windows such as the status bar. If true, adjusts the padding of this view to leave space for the system windows. Will only take effect if this view is in a non-embedded activity.

Must be a boolean value, either “true” or “false”.

This may also be a reference to a resource (in the form “@[package:]type:name”) or theme attribute (in the form “?[package:][type:]name”) containing a value of this type.

This corresponds to the global attribute resource symbol fitsSystemWindows.

#85 Best answer 2 of Toolbar overlapping below status bar(Score: 18)

Created: 2016-06-28 Last updated: 2016-08-30

Just set this to v21/styles.xml file

 <item name="android:windowDrawsSystemBarBackgrounds">true</item>
 <item name="android:statusBarColor">@color/colorPrimaryDark</item>

and be sure

 <item name="android:windowTranslucentStatus">false</item>

See also original question in stackoverflow

#86: How to center the content inside a linear layout? (Score: 175)

Created: 2013-08-05

Tags: android, android-layout, android-linearlayout

I’m trying to center an ImageView inside a LinearLayout horizontally and vertically, but I just can’t do it. The main reason why I’m not using a RelativeLayout for that is because I need the layout_weight (my Activity consists of four columns that should be equally divided, and also responsive to different screen widths, each column having an ImageView centered and unstretched).

Here is my xml so far:

<LinearLayout 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"
    android:background="#000"
    android:baselineAligned="false"
    android:gravity="center"
    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=".Main" >

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1" >
        
        <ImageView
            android:id="@+id/imageButton_speak"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_speak" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1" >

        <ImageView
            android:id="@+id/imageButton_readtext"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_readtext" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1" >

        <ImageView
            android:id="@+id/imageButton_edit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_edit" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1" >

        <ImageView
            android:id="@+id/imageButton_config"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_config" />
    </LinearLayout>
</LinearLayout>

#86 Best answer 1 of How to center the content inside a linear layout? (Score: 413)

Created: 2013-08-05 Last updated: 2017-04-28

android:gravity handles the alignment of its children,

android:layout_gravity handles the alignment of itself.

So use one of these.

<LinearLayout 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"
    android:background="#000"
    android:baselineAligned="false"
    android:gravity="center"
    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=".Main" >

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center" >

        <ImageView
            android:id="@+id/imageButton_speak"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_speak" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center" >

        <ImageView
            android:id="@+id/imageButton_readtext"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_readtext" />
    </LinearLayout>

    ...
</LinearLayout>

or

<LinearLayout 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"
    android:background="#000"
    android:baselineAligned="false"
    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=".Main" >

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1" >

        <ImageView
            android:id="@+id/imageButton_speak"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_speak" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1" >

        <ImageView
            android:id="@+id/imageButton_readtext"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:background="@drawable/image_bg"
            android:src="@drawable/ic_readtext" />
    </LinearLayout>

    ...
</LinearLayout>

#86 Best answer 2 of How to center the content inside a linear layout?(Score: 41)

Created: 2013-08-05 Last updated: 2019-04-01

android:layout_gravity is used for the layout itself

Use android:gravity="center" for children of your LinearLayout

So your code should be:

<LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:layout_weight="1" >

See also original question in stackoverflow

#87: Vertical line using XML drawable (Score: 173)

Created: 2010-04-17 Last updated: 2013-12-30

Tags: android, android-layout, line, android-xml, android-drawable

I’m trying to figure out how to define a vertical line (1dp thick) to be used as a drawable.

To make a horizontal one, it’s pretty straightforward:

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="line">
    <stroke android:width="1dp" android:color="#0000FF"/>
    <size android:height="50dp" />     
</shape>

The question is, how to make this line vertical?

Yes, there are workarounds, such as drawing a rectangle shape 1px thick, but that complicates the drawable XML, if it consists of multiple <item> elements.

Anyone had any chance with this?

UPDATE

Case is still unsolved. However, For anyone on a Android documentation crusade - you might find this useful: Missing Android XML Manual

UPDATE

I found no other way other than the one that I marked as correct. It does the trick though feels a bit “heavy”, thus if you happen to know the answer don’t forget to share ;)

#87 Best answer 1 of Vertical line using XML drawable (Score: 413)

Created: 2010-04-17 Last updated: 2020-08-13

Instead of a shape, you could try a View:

<View
    android:layout_width="1dp"
    android:layout_height="match_parent"
    android:background="#FF0000FF" />

I have only used this for horizontal lines, but I would think it would work for vertical lines as well.

Use:

<View
    android:layout_width="match_parent"
    android:layout_height="1dp"
    android:background="#FF0000FF" />

for a horizontal line.

#87 Best answer 2 of Vertical line using XML drawable(Score: 114)

Created: 2010-09-22 Last updated: 2014-10-06

You can nest your shape inside a rotate tag.

<rotate xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromDegrees="90"
    android:toDegrees="90">
    <shape 
        android:shape="line">
        <stroke
            android:width="1dp"
            android:color="#ff00ff"
            android:dashWidth="1dp"
            android:dashGap="2dp" />
    </shape>
</rotate>

However, the only problem is the layout params defined in your layout xml will be the dimensions used to draw the original shape. Meaning if you want your line to be 30dp tall, you need to define a layout_width of 30dp in your layout xml. But the final width will also be 30dp in that case, which is likely undesirable for most situations. This essentially means both width and height have to be the same value, the value of your desired length for the line. I couldn’t figure out how to fix this.

This seems to be the “android way” solution, but unless there’s some fix or workaround for the dimensions issue I mention then this likely won’t work for most people. What we really need is an orientation attribute in <shape/> or <stroke/>.

You can also try referencing another drawable in the rotate tag’s attributes, such as:

<rotate xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromDegrees="90"
    android:toDegrees="90"
    android:drawable="@drawable/horizontal_line" />

However I haven’t tested this and expect it to have the same issues.

– EDIT –

Oh, I actually figured out a fix. You can use a negative margin in your layout xml to get rid of the undesired extra space. Such as:

<ImageView
    android:layout_width="35dp"
    android:layout_height="35dp"
    android:layout_marginLeft="-15dp"
    android:layout_marginRight="-15dp"
    android:src="@drawable/dashed_vertical_line" />

See also original question in stackoverflow

#88: Why does LayoutInflater ignore the layout_width and layout_height layout parameters I've specified? (Score: 172)

Created: 2011-02-17 Last updated: 2017-05-23

Tags: android, android-layout

I’ve had severe trouble getting LayoutInflater to work as expected, and so did other people: https://stackoverflow.com/questions/4735847/help-for-using-layoutinflator-to-add-views-at-runtime.

Why does LayoutInflater ignore the layout parameters I’ve specified? E.g. why are the layout_width and layout_height values from my resources XML not honored?

#88 Best answer 1 of Why does LayoutInflater ignore the layout_width and layout_height layout parameters I've specified? (Score: 397)

Created: 2011-02-17 Last updated: 2018-11-29

I’ve investigated this issue, referring to the LayoutInflater docs and setting up a small sample demonstration project. The following tutorials shows how to dynamically populate a layout using LayoutInflater.

Before we get started see what LayoutInflater.inflate() parameters look like:

  • resource: ID for an XML layout resource to load (e.g., R.layout.main_page)

  • root: Optional view to be the parent of the generated hierarchy (if attachToRoot is true), or else simply an object that provides a set of LayoutParams values for root of the returned hierarchy (if attachToRoot is false.)

  • attachToRoot: Whether the inflated hierarchy should be attached to the root parameter? If false, root is only used to create the correct subclass of LayoutParams for the root view in the XML.

  • Returns: The root View of the inflated hierarchy. If root was supplied and attachToRoot is true, this is root; otherwise it is the root of the inflated XML file.

Now for the sample layout and code.

Main layout (main.xml):

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

Added into this container is a separate TextView, visible as small red square if layout parameters are successfully applied from XML (red.xml):

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="25dp"
    android:layout_height="25dp"
    android:background="#ff0000"
    android:text="red" />

Now LayoutInflater is used with several variations of call parameters

public class InflaterTest extends Activity {

    private View view;

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

      setContentView(R.layout.main);
      ViewGroup parent = (ViewGroup) findViewById(R.id.container);

      // result: layout_height=wrap_content layout_width=match_parent
      view = LayoutInflater.from(this).inflate(R.layout.red, null);
      parent.addView(view);

      // result: layout_height=100 layout_width=100
      view = LayoutInflater.from(this).inflate(R.layout.red, null);
      parent.addView(view, 100, 100);

      // result: layout_height=25dp layout_width=25dp
      // view=textView due to attachRoot=false
      view = LayoutInflater.from(this).inflate(R.layout.red, parent, false);
      parent.addView(view);

      // result: layout_height=25dp layout_width=25dp 
      // parent.addView not necessary as this is already done by attachRoot=true
      // view=root due to parent supplied as hierarchy root and attachRoot=true
      view = LayoutInflater.from(this).inflate(R.layout.red, parent, true);
    }
}

The actual results of the parameter variations are documented in the code.

SYNOPSIS: Calling LayoutInflater without specifying root leads to inflate call ignoring the layout parameters from the XML. Calling inflate with root not equal null and attachRoot=true does load the layout parameters, but returns the root object again, which prevents further layout changes to the loaded object (unless you can find it using findViewById()). The calling convention you most likely would like to use is therefore this one:

loadedView = LayoutInflater.from(context)
                .inflate(R.layout.layout_to_load, parent, false);

To help with layout issues, the Layout Inspector is highly recommended.

#88 Best answer 2 of Why does LayoutInflater ignore the layout_width and layout_height layout parameters I've specified?(Score: 8)

Created: 2016-02-19

andig is correct that a common reason for LayoutInflater ignoring your layout_params would be because a root was not specified. Many people think you can pass in null for root. This is acceptable for a few scenarios such as a dialog, where you don’t have access to root at the time of creation. A good rule to follow, however, is that if you have root, give it to LayoutInflater.

I wrote an in-depth blog post about this that you can check out here:

https://www.bignerdranch.com/blog/understanding-androids-layoutinflater-inflate/

See also original question in stackoverflow

#89: Flinging with RecyclerView + AppBarLayout (Score: 171)

Created: 2015-06-18 Last updated: 2015-06-18

Tags: android, android-layout, android-design-library, android-appcompat

I am using the new CoordinatorLayout with AppBarLayout and CollapsingToolbarLayout. Below AppBarLayout, I have a RecyclerView with a list of content.

I have verified that fling scrolling works on the RecyclerView when I am scrolling up and down the list. However, I would also like the AppBarLayout to smoothly scroll during expansion.

When scrolling up to expand the CollaspingToolbarLayout, scrolling immediately stops once lifting your finger off the screen. If you scroll up in a quick motion, sometimes the CollapsingToolbarLayout re-collapses as well. This behavior with the RecyclerView seems to function much differently than when using a NestedScrollView.

I’ve tried to set different scroll properties on the recyclerview but I haven’t been able to figure this out.

Here is a video showing some of the scrolling issues. https://youtu.be/xMLKoJOsTAM

Here is an example showing the issue with the RecyclerView (CheeseDetailActivity). https://github.com/tylerjroach/cheesesquare

Here is the original example that uses a NestedScrollView from Chris Banes. https://github.com/chrisbanes/cheesesquare

#89 Best answer 1 of Flinging with RecyclerView + AppBarLayout (Score: 114)

Created: 2015-09-08 Last updated: 2017-05-23

The answer of Kirill Boyarshinov was almost correct.

The main problem is that the RecyclerView sometimes is giving incorrect fling direction, so if you add the following code to his answer it works correctly:

public final class FlingBehavior extends AppBarLayout.Behavior {
    private static final int TOP_CHILD_FLING_THRESHOLD = 3;
    private boolean isPositive;

    public FlingBehavior() {
    }

    public FlingBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onNestedFling(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, float velocityX, float velocityY, boolean consumed) {
        if (velocityY > 0 && !isPositive || velocityY < 0 && isPositive) {
            velocityY = velocityY * -1;
        }
        if (target instanceof RecyclerView && velocityY < 0) {
            final RecyclerView recyclerView = (RecyclerView) target;
            final View firstChild = recyclerView.getChildAt(0);
            final int childAdapterPosition = recyclerView.getChildAdapterPosition(firstChild);
            consumed = childAdapterPosition > TOP_CHILD_FLING_THRESHOLD;
        }
        return super.onNestedFling(coordinatorLayout, child, target, velocityX, velocityY, consumed);
    }

    @Override
    public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, int dx, int dy, int[] consumed) {
        super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed);
        isPositive = dy > 0;
    }
}

I hope that this helps.

#89 Best answer 2 of Flinging with RecyclerView + AppBarLayout(Score: 69)

Created: 2015-08-24 Last updated: 2016-07-29

Seems that v23 update did not fix it yet.

I have found sort of of hack to fix it with flinging down. The trick is to reconsume fling event if ScrollingView’s top child is close to the beginning of data in Adapter.

public final class FlingBehavior extends AppBarLayout.Behavior {

    public FlingBehavior() {
    }

    public FlingBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onNestedFling(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, float velocityX, float velocityY, boolean consumed) {
        if (target instanceof ScrollingView) {
            final ScrollingView scrollingView = (ScrollingView) target;
            consumed = velocityY > 0 || scrollingView.computeVerticalScrollOffset() > 0;
        }
        return super.onNestedFling(coordinatorLayout, child, target, velocityX, velocityY, consumed);
    }
}

Use it in your layout like that:

 <android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:layout_behavior="your.package.FlingBehavior">
    <!--your views here-->
 </android.support.design.widget.AppBarLayout>

EDIT: Fling event reconsuming is now based on verticalScrollOffset instead of amount of items on from top of RecyclerView.

EDIT2: Check target as ScrollingView interface instance instead of RecyclerView. Both RecyclerView and NestedScrollingView implement it.

See also original question in stackoverflow

#90: What is the 'app' Android XML namespace? (Score: 171)

Created: 2014-11-01 Last updated: 2016-09-20

Tags: android, xml, android-layout, xml-namespaces, android-tools-namespace

Here is an example of the app namespace that I’ve seen from a res/menu/main.xml file

<menu 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"
tools:context=".MainActivity" >
<item android:id="@+id/action_settings"
    android:title="@string/action_settings"
    android:orderInCategory="100"
    app:showAsAction="never" />
</menu>

What purpose does the app namespace serve? Is it a “standard” Android XML namespace? Are the same value options available for the same attribute placed in two different namespaces (e.g. app:showAsAction and android:showAsAction).

From the docs: android:showAsAction=["ifRoom" | "never" | "withText" | "always" | "collapseActionView"]

i.e., would the line in the above example mean something else if the attribute were instead:

android:showAsAction="never"

It almost looks like it might be some sort of “subclassing” mechanism, but I can’t seem to find any real documentation on the app namespace from Google/Android sources.

#90 Best answer 1 of What is the 'app' Android XML namespace? (Score: 222)

Created: 2014-11-01

The app namespace is not specific to a library, but it is used for all attributes defined in your app, whether by your code or by libraries you import, effectively making a single global namespace for custom attributes - i.e., attributes not defined by the android system.

In this case, the appcompat-v7 library uses custom attributes mirroring the android: namespace ones to support prior versions of android (for example: android:showAsAction was only added in API11, but app:showAsAction (being provided as part of your application) works on all API levels your app does) - obviously using the android:showAsAction wouldn’t work on API levels where that attribute is not defined.

#90 Best answer 2 of What is the 'app' Android XML namespace?(Score: 0)

Created: 2019-06-20

You can get some explaination from this link

XML namespace

Namespace declaration An XML namespace is declared using the reserved XML attribute xmlns or xmlns:prefix, the value of which must be a valid namespace name.

For example, the following declaration maps the “xhtml:” prefix to the XHTML namespace:

xmlns:xhtml=“http://www.w3.org/1999/xhtml"

Any element or attribute whose name starts with the prefix “xhtml:” is considered to be in the XHTML namespace, if it or an ancestor has the above namespace declaration.

It is also possible to declare a default namespace. For example:

xmlns=“http://www.w3.org/1999/xhtml"

In this case, any element without a namespace prefix is considered to be in the XHTML namespace, if it or an ancestor has the above default namespace declaration.

If there is no default namespace declaration in scope, the namespace name has no value.[6] In that case, an element without an explicit namespace prefix is considered not to be in any namespace.

Attributes are never subject to the default namespace. An attribute without an explicit namespace prefix is considered not to be in any namespace.

See also original question in stackoverflow


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