AlertDialog
Android AlertDialog can be used to display the dialog message with OK and Cancel buttons. It can be used to interrupt and ask the user about his/her choice to continue or discontinue.
Android AlertDialog is composed of three regions: title, content area and action buttons.
Android AlertDialog is the subclass of Dialog class.
Methods of AlertDialog class
| Method | Description |
|---|---|
| public AlertDialog.Builder setTitle(CharSequence) | This method is used to set the title of AlertDialog. |
| public AlertDialog.Builder setMessage(CharSequence) | This method is used to set the message for AlertDialog. |
| public AlertDialog.Builder setIcon(int) | This method is used to set the icon over AlertDialog. |
Android AlertDialog Example
Let's see a simple example of android alert dialog.
activity_main.xml
You can have multiple components, here we are having only a textview.
File: activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="example.javatpoint.com.alertdialog.MainActivity">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/button"
android:text="Close app"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
<android.support.constraint.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="example.javatpoint.com.alertdialog.MainActivity">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/button"
android:text="Close app"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
strings.xml
Optionally, you can store the dialog message and title in the strings.xml file.
File: strings.xml
<resources>
<string name="app_name">AlertDialog</string>
<string name="dialog_message">Welcome to Alert Dialog</string>
<string name="dialog_title">Javatpoint Alert Dialog</string>
</resources>
<string name="app_name">AlertDialog</string>
<string name="dialog_message">Welcome to Alert Dialog</string>
<string name="dialog_title">Javatpoint Alert Dialog</string>
</resources>
Activity class
Let's write the code to create and show the AlertDialog.
File: MainActivity.java
package example.javatpoint.com.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.app.AlertDialog;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
Button closeButton;
AlertDialog.Builder builder;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
closeButton = (Button) findViewById(R.id.button);
builder = new AlertDialog.Builder(this);
closeButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Uncomment the below code to Set the message and title from the strings.xml file
builder.setMessage(R.string.dialog_message) .setTitle(R.string.dialog_title);
//Setting message manually and performing action on button click
builder.setMessage("Do you want to close this application ?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
finish();
Toast.makeText(getApplicationContext(),"you choose yes action for alertbox",
Toast.LENGTH_SHORT).show();
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// Action for 'NO' Button
dialog.cancel();
Toast.makeText(getApplicationContext(),"you choose no action for alertbox",
Toast.LENGTH_SHORT).show();
}
});
//Creating dialog box
AlertDialog alert = builder.create();
//Setting the title manually
alert.setTitle("AlertDialogExample");
alert.show();
}
});
}
}
import android.content.DialogInterface;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.app.AlertDialog;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
Button closeButton;
AlertDialog.Builder builder;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
closeButton = (Button) findViewById(R.id.button);
builder = new AlertDialog.Builder(this);
closeButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Uncomment the below code to Set the message and title from the strings.xml file
builder.setMessage(R.string.dialog_message) .setTitle(R.string.dialog_title);
//Setting message manually and performing action on button click
builder.setMessage("Do you want to close this application ?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
finish();
Toast.makeText(getApplicationContext(),"you choose yes action for alertbox",
Toast.LENGTH_SHORT).show();
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// Action for 'NO' Button
dialog.cancel();
Toast.makeText(getApplicationContext(),"you choose no action for alertbox",
Toast.LENGTH_SHORT).show();
}
});
//Creating dialog box
AlertDialog alert = builder.create();
//Setting the title manually
alert.setTitle("AlertDialogExample");
alert.show();
}
});
}
}
Output:
