AlertDialog Example

Let's create a simple program as follows: Whenever the user clicks on a button, an AlertDialog appears on the screen. Then the user chooses 1 out of 3 options and the option selected is shown using Toast.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="com.example.android.alertdialog.MainActivity">

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:text="Learning AlertDialog"
        android:textSize="40sp"
        />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Open AlertDialog"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="100dp"
        android:onClick="openDialog"
        />

</RelativeLayout>

MainActivity.java

package com.example.android.alertdialog;

import android.content.DialogInterface;

import android.os.Bundle;

import android.support.v7.app.AlertDialog;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.widget.Toast;


public class MainActivity extends AppCompatActivity {

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

    }

    public void openDialog(View v){

        AlertDialog.Builder builder = new AlertDialog.Builder(this);

        //Setting AlertDialog Characteristics

        builder.setTitle("Learning Dialog");

        builder.setMessage("I Love StudyTonight");

        //Set Positive Button

        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {

            @Override

            public void onClick(DialogInterface dialog, int which) {

                Toast.makeText(getApplicationContext(),"OK button was pressed",Toast.LENGTH_LONG).show();

          }
        });

        //Set Negative Button

        builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {

                Toast.makeText(getApplicationContext(),"Cancel button was pressed",Toast.LENGTH_LONG).show();

            }
        });

        //Set Neutral Button
        builder.setNeutralButton("Remind me later", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {

                Toast.makeText(getApplicationContext(),"Remind me later button was pressed",Toast.LENGTH_LONG).show();

            }
        });

        //Creating AlertDialog
        AlertDialog dialog = builder.create();

        //Displaying AlertDialog
        dialog.show();
    }
}