MainActivity.java file

package com.notesbazzar.alertdialog;

import android.app.AlertDialog; import android.content.DialogInterface;

import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

Button click,two,three;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    click = (Button)findViewById(R.id.button);
    two = (Button)findViewById(R.id.button2);
    three = (Button)findViewById(R.id.button3);
    three.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            AlertDialog.Builder alertdialog = new AlertDialog.Builder(MainActivity.this);
            alertdialog.setTitle("Alert Dialog 3");
            alertdialog.setMessage("Welcome");
            alertdialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Toast.makeText(MainActivity.this, "Yes", Toast.LENGTH_SHORT).show();
                }
            });
            alertdialog.setNegativeButton("no", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Toast.makeText(MainActivity.this, "No", Toast.LENGTH_SHORT).show();
                }
            });
            alertdialog.setNeutralButton("Cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Toast.makeText(MainActivity.this, "cancel", Toast.LENGTH_SHORT).show();
                }
            });
            alertdialog.show();
        }

    });

    two.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this);

            alertDialog.setTitle("Alert Dialog2");
            alertDialog.setMessage("Welcome");

            alertDialog.setPositiveButton("YES", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int which) {

                    // Write your code here to invoke YES event
                    Toast.makeText(getApplicationContext(), "You clicked on YES", Toast.LENGTH_SHORT).show();
                }
            });

            // Setting Negative "NO" Button
            alertDialog.setNegativeButton("NO", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    // Write your code here to invoke NO event
                    Toast.makeText(getApplicationContext(), "You clicked on NO", Toast.LENGTH_SHORT).show();
                    dialog.cancel();
                }
            });



            // Showing Alert Message
            alertDialog.show();
        }
    });

    click.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            AlertDialog alertDialog = new AlertDialog.Builder(
                    MainActivity.this).create();

            alertDialog.setTitle("Alert Dialog");

            // Setting Dialog Message
            alertDialog.setMessage("Welcome to AndroidHive.info");

            alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    // Write your code here to execute after dialog closed
                    Toast.makeText(getApplicationContext(), "You clicked on OK", Toast.LENGTH_SHORT).show();
                }
            });

            alertDialog.show();


        }
    });


}

}