Display an Alert Box in Android - Android Tutorial

by techizhub.com on June 19, 2017 in Android Tutorials

Did you heard aboout Android Alertbox or dialog box?But i am sure you have seen it several times on your android phone.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 modal events that require users to take an action before they can proceed.See more about it here

In this post we are going to create an alertbox when user want to exit from your application.Its a very simple task to create an alertbox .Ok let us do it

STEP 1:

Create a new android studio project.Learn more about this step from this post

STEP 2:

activity_main.xml

RelativeLayout 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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Next Activity"/>

</RelativeLayout>

So this is our MainActivity.java

public class MainActivity extends ActionBarActivity {

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

}

Add this to MainActivity.java

 @Override
    public void onBackPressed()
    {

        new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Exit").setMessage("Sure you want to close this App").setPositiveButton("OK",new DialogInterface.OnClickListener()
        {
            @Override
            public void onClick(DialogInterface dialog,int which)
            {

                Intent  intent =new Intent(Intent.ACTION_MAIN);
                intent.addCategory(Intent.CATEGORY_HOME);
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
                MainActivity.this.finish();

            }


        }).setNegativeButton("Cancel",null).show();
    }

So our MainActivity.java will look like this

public class MainActivity extends ActionBarActivity {

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


    @Override
    public void onBackPressed()
    {

        new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Exit").setMessage("Sure you want to close this App").setPositiveButton("OK",new DialogInterface.OnClickListener()
        {
            @Override
            public void onClick(DialogInterface dialog,int which)
            {

                Intent  intent =new Intent(Intent.ACTION_MAIN);
                intent.addCategory(Intent.CATEGORY_HOME);
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
                MainActivity.this.finish();

            }


        }).setNegativeButton("Cancel",null).show();
    }

}