A dialog is a small window that prompts the user to make a decision or enter additional information. A dialog does not fill the screen and is normally used for model events that require users to take an action before they can proceed. Custom alert Example Simlpe Alert Example For this ,we need :- 1 . MainActivity.java 2. avtivity_main.xml 3. custom.xml MainActivity.java package com.blogspot.help2computer.alertdialogs; import android.app.Dialog; import android.os.Bundle; import android.support.v7.app.AlertDialog; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.view.Window; import android.widget.Button; public class MainActivity extends AppCompatActivity { Button popup ; @Override protected void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout. activity_main ); popup = (Button) findViewById(R.id. button_popup ); popUpAlert(); ...