android – BottomSheetDialog background blinking-ThrowExceptions

Exception or error:

BottomSheetDialog‘s background is blinking when switching between apps. What am I doing wrong ?

MainActivity.java

public class MainActivity extends AppCompatActivity {

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

        setContentView(R.layout.activity_main);

        findViewById(R.id.btn1).setOnClickListener(v -> {
            BottomSheetDialog bottomSheetDialog = new BottomSheetDialog(MainActivity.this);
            bottomSheetDialog.setContentView(R.layout.content);
            bottomSheetDialog.show();
        });
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
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">

    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

content.xml

<?xml version="1.0" encoding="utf-8"?>
<View 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="300dp"
    android:background="#F00" />

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.holtaf.testandroidapplication">

    <application
        android:allowBackup="true"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/Theme.AppCompat.Light.DarkActionBar">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

My appcompat version is 27.1.1.

enter image description here

How to solve:

The main reason for the flickering is due to the default styling of the BottomSheetDialog which defines a default animation and the dim behavior.

We can resolve the above issue by defining a custom theme using bottomSheetDialogTheme which in turn:

  1. Disables the default window animation for the BottomSheet by setting windowAnimationStyle to @null.
  2. Sets the backgroundDimEnabled attribute to false.

Example:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>

    <item name="bottomSheetDialogTheme">@style/AppTheme.BottomSheetDialog</item>
</style>

<style name="AppTheme.BottomSheetDialog" parent="Theme.Design.BottomSheetDialog">
    <item name="android:windowAnimationStyle">@null</item>
    <item name="android:backgroundDimEnabled">false</item>

    <!-- optional -->
    <item name="android:windowBackground">#99323232</item> 
</style>

###

Use Coordinate layout instead of constraint layout, and define bottomsheet layout in xml like below

    <android.support.design.widget.CoordinatorLayout 
        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">

         <Button
            android:id="@+id/btn1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Hello World!"
            android:layout_gravity="center" />

         <android.support.v4.widget.NestedScrollView 
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:id="@+id/bottom_sheet_map"
            android:layout_width="match_parent"
            android:layout_height="150dp"
            app:layout_behavior="android.support.design.widget.BottomSheetBehavior">

               <include layout="@layout/layout_bottom_sheet" />
        </android.support.v4.widget.NestedScrollView>
    </android.support.design.widget.CoordinatorLayout>

In Java Class Use like this.

    private BottomSheetBehavior mBottomSheetBehavior;
    private View bottomSheet;
    private isBottomSheetExpand = false;
    ...
    btn1.setOnClickListner(new View.OncliView.OnClickListener(){
    @Override
        public void onClick(View v) {
            if(isBottomSheetExpand){
                openBottomSheet();
            }else{
                closeBottomSheet();
            }
        }
    });
    ...
    public void closeBottomSheet() {
       if (mBottomSheetBehavior.getState() == BottomSheetBehavior.STATE_EXPANDED) {
            mBottomSheetBehavior.setState(BottomSheetBehavior.STATE_COLLAPSED);
            isBottomSheetExpand = false;
        }
    }

    public void openBottomSheet() {
        if (mBottomSheetBehavior.getState() != BottomSheetBehavior.STATE_EXPANDED) {
            mBottomSheetBehavior.setState(BottomSheetBehavior.STATE_EXPANDED);
            isBottomSheetExpand = true;
        }
    }

###

According to documentation the setPeekHeight method is responsible for the pop up behavior. Using the

bottomSheet.setState(STATE_HIDDEN) should do the trick.

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