How to show a alert dialog to confirm that the user wishes to exit in an android studio with source code

 How to show alert dialog when clicking on the back press button in android studio

In this post, I am going to show you how to show the alert dialog box when the user presses the back button.

When a user clicks on back then a dialog shows and displays a message like do you want to exit or do you really want to exit.

The first alert dialog will show, the latter will be the exit in an android.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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">

    <TextView
        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" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package com.example.alertdialog;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.DialogInterface;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate ( savedInstanceState );
        setContentView ( R.layout.activity_main );
    }
    @SuppressLint("ResourceAsColor")
    public  void onBackPressed(){
        AlertDialog.Builder builder=new AlertDialog.Builder ( this );
builder.setTitle ( "New simple Alert dialog" );
builder.setIcon ( R.drawable.ic_exit_to_app_black_24dp );
builder.setMessage ( "Do you realy wnat to exit?" )
.setCancelable ( false )
        .setPositiveButton ( "Yes", new DialogInterface.OnClickListener () {
            @Override
            public void onClick(DialogInterface dialog, int which) {
finish ();
            }
        } )
        .setNegativeButton ( "no", new DialogInterface.OnClickListener () {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel ();
            }
        } );
AlertDialog alertDialog=builder.create ();
alertDialog.show ();
alertDialog.getButton ( AlertDialog.BUTTON_POSITIVE ).setBackgroundColor ( getResources ().getColor ( R.color.green) );
alertDialog.getButton ( AlertDialog.BUTTON_NEGATIVE ).setBackgroundColor ( getResources ().getColor ( R.color.red) );
//SET HEIGHT AND WIDTH OF ALERT DIALOG BOX
int width=(int)(getResources ().getDisplayMetrics ().widthPixels*0.85);
int height=(int)(getResources ().getDisplayMetrics ().heightPixels*0.30);
alertDialog.getWindow ().setLayout ( width,height );
alertDialog.getWindow ().setBackgroundDrawableResource ( R.drawable.ic_launcher_background );
    }
}

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