Get display information using DisplayMetrics, in Multi-Window Mode

The class android.util.DisplayMetrics is a structure describing general information about a display, such as its size, density, and font scaling. Here show how to get display information (specially heightPixels and widthPixels) in Multi-Window Mode.

package com.blogspot.android_er.androidmultiwindow;

        import android.content.res.Configuration;
        import android.os.Bundle;
        import android.support.v7.app.AppCompatActivity;
        import android.util.DisplayMetrics;
        import android.widget.TextView;
        import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    TextView textPrompt;
    TextView textInfo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textPrompt = (TextView)findViewById(R.id.prompt);
        textInfo = (TextView)findViewById(R.id.info);

        if(isInMultiWindowMode()){
            textPrompt.setText("onCreate run In Multi Window Mode ");
        }else{
            textPrompt.setText("onCreate run NOT In Multi Window Mode ");
        }

        Toast.makeText(MainActivity.this,
                "onCreate() called", Toast.LENGTH_LONG).show();

        showDisplayInfo();
    }

    @Override
    public void onMultiWindowModeChanged(boolean isInMultiWindowMode) {
        super.onMultiWindowModeChanged(isInMultiWindowMode);

        if(isInMultiWindowMode){
            textPrompt.setText("It is In Multi Window Mode ");
        }else{
            textPrompt.setText("It is NOT In Multi Window Mode ");
        }

        Toast.makeText(MainActivity.this,
                "onMultiWindowModeChanged() called", Toast.LENGTH_LONG).show();

        showDisplayInfo();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);

        Toast.makeText(MainActivity.this,
                "onConfigurationChanged() called", Toast.LENGTH_LONG).show();

        showDisplayInfo();
    }

    private void showDisplayInfo(){
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);

        String strScreenDIP = "";
        strScreenDIP += "The logical density of the display: " + dm.density + "\n";
        strScreenDIP += "The screen density expressed as dots-per-inch: " + dm.densityDpi +"\n";
        strScreenDIP += "The absolute height of the display in pixels: " + dm.heightPixels +"\n";
        strScreenDIP += "The absolute width of the display in pixels: " + dm.widthPixels + "\n";
        strScreenDIP += "A scaling factor for fonts displayed on the display: " 
                + dm.scaledDensity + "\n";
        strScreenDIP += "The exact physical pixels per inch of the screen in the X dimension: " 
                + dm.xdpi + "\n";
        strScreenDIP += "The exact physical pixels per inch of the screen in the Y dimension: " 
                + dm.ydpi + "\n";

        textInfo.setText(strScreenDIP);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<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:padding="16dp"
    android:orientation="vertical"
    tools:context="com.blogspot.android_er.androidmultiwindow.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold"/>
    <TextView
        android:id="@+id/prompt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:textStyle="bold"/>
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <TextView
            android:id="@+id/info"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="20dp"/>
    </ScrollView>

</LinearLayout>