Message dialogs provide information to the user. Message dialogs are created with the JOptionPane.showMessageDialog() method.
We call the static showMessageDialog() method of the JOptionPane class to create a message dialog. We provide the dialog’s parent, message text, title, and message type. The message type is one of the following constants :
- ERROR_MESSAGE
- WARNING_MESSAGE
- QUESTION_MESSAGE
- INFORMATION_MESSAGE
Methods Used :
- setLayout(…): method helps us to set the layout of the container, often a JPanel, to say FlowLayout, BorderLayout, GridLayout, null layout, or whatever layout we want to add on container.
- setBounds(…): method is used to set the location and size of components like JButton, and is only useful if null layout is used in JFrame.
-
setVisible(…): method is used to set the Visibility status of JFrame.
- setVisible(true) will set JFrame visible to user.
- setVisible(false) will set JFrame not visible to user.
- getSource(): An event object contains a reference to the component that generated the event. To extract that reference from the event object we use getSource() Method.
- add(): It is used to add components like JButton etc, to the container of JFrame.
Below is the implementation of above discussed method to show Message Dialogs :
Java
// Java program to show ERROR_MESSAGE dialog // in Java. Importing different Package. import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Demo extends JFrame implements ActionListener
{ // Declaration of object of JButton class.
JButton b1;
// Constructor of Demo class
Demo()
{
// Setting layout as null of JFrame.
this .setLayout( null );
// Initialization of object of "JButton" class.
b1 = new JButton( "Button 1" );
// Setting Bounds of a JButton.
b1.setBounds( 130 , 05 , 100 , 50 );
//"this" keyword in java refers to current object.
// Adding JButton on JFrame.
this .add(b1);
// Adding Listener toJButton.
b1.addActionListener( this );
}
// Override Method
public void actionPerformed(ActionEvent evt)
{
if (evt.getSource() == b1)
{
// Code To popup an ERROR_MESSAGE Dialog.
JOptionPane.showMessageDialog( this , "Enter a valid Number" ,
"ERROR" , JOptionPane.ERROR_MESSAGE);
}
}
} class MessageDialogs1 {
// Driver code
public static void main(String args[])
{
// Creating Object of demo class.
Demo f = new Demo();
// Setting Bounds of a Frame.
f.setBounds( 200 , 200 , 400 , 300 );
// Setting Resizable status of frame as false
f.setResizable( false );
// Setting Visible status of frame as true.
f.setVisible( true );
}
} |
Output :
Java
// Java program to show WARNING_MESSAGE dialog // in Java. Importing different Package. import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Demo extends JFrame implements ActionListener
{ // Declaration of object of JButton class.
JButton b1;
// Constructor of Demo class
Demo()
{
// Setting layout as null of JFrame.
this .setLayout( null );
// Initialization of object of "JButton" class.
b1 = new JButton( "Button 2" );
// Setting Bounds of a JButton.
b1.setBounds( 130 , 05 , 100 , 50 );
//"this" keyword in java refers to current object.
// Adding JButton on JFrame.
this .add(b1);
// Adding Listener toJButton.
b1.addActionListener( this );
}
// Override Method
public void actionPerformed(ActionEvent evt)
{
if (evt.getSource() == b1) {
// Code To popup an WARNING_MESSAGE Dialog.
JOptionPane.showMessageDialog( this , "Enter a valid String" ,
"WARNING" , JOptionPane.WARNING_MESSAGE);
}
}
} class MessageDialogs2 {
// Driver code
public static void main(String args[])
{
// Creating Object of demo class.
Demo f = new Demo();
// Setting Bounds of a Frame.
f.setBounds( 200 , 200 , 400 , 300 );
// Setting Resizable status of frame as false
f.setResizable( false );
// Setting Visible status of frame as true.
f.setVisible( true );
}
} |
Output :
Java
// Java program to show QUESTION_MESSAGE // dialog in Java. Importing different Package. import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Demo extends JFrame implements ActionListener
{ // Declaration of object of JButton class.
JButton b1;
// Constructor of Demo class
Demo()
{
// Setting layout as null of JFrame.
this .setLayout( null );
// Initialization of object of "JButton" class.
b1 = new JButton( "Button 3" );
// Setting Bounds of a JButton.
b1.setBounds( 130 , 05 , 100 , 50 );
//"this" keyword in java refers to current object.
// Adding JButton on JFrame.
this .add(b1);
// Adding Listener toJButton.
b1.addActionListener( this );
}
// Override Method
public void actionPerformed(ActionEvent evt)
{
if (evt.getSource() == b1)
{
// Code TO popup a QUESTION_MESSAGE Dialog.
JOptionPane.showMessageDialog( this , "Do you want to quit" ,
"Question" , JOptionPane.QUESTION_MESSAGE);
}
}
} class MessageDialogs3 {
// Driver code
public static void main(String args[])
{
// Creating Object of demo class.
Demo f = new Demo();
// Setting Bounds of a Frame.
f.setBounds( 200 , 200 , 400 , 300 );
// Setting Resizable status of frame as false
f.setResizable( false );
// Setting Visible status of frame as true.
f.setVisible( true );
}
} |
Output :
Java
// Java program to show INFORMATION_MESSAGE // dialog in Java. Importing different Package. import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class Demo extends JFrame implements ActionListener
{ // Declaration of object of JButton class.
JButton b1;
// Constructor of Demo class
Demo()
{
// Setting layout as null of JFrame.
this .setLayout( null );
// Initialization of object of "JButton" class.
b1 = new JButton( "Button 4" );
// Setting Bounds of a JButton.
b1.setBounds( 130 , 05 , 100 , 50 );
//"this" keyword in java refers to current object.
// Adding JButton on JFrame.
this .add(b1);
// Adding Listener toJButton.
b1.addActionListener( this );
}
// Override Method
public void actionPerformed(ActionEvent evt)
{
if (evt.getSource() == b1)
{
// Code To popup an INFORMATION_MESSAGE Dialog.
JOptionPane.showMessageDialog( this , "You Pressed Button FOUR" ,
"INFORMATION" ,
JOptionPane.INFORMATION_MESSAGE);
}
}
} class MessageDialogs4 {
// Driver code
public static void main(String args[])
{
// Creating Object of demo class.
Demo f = new Demo();
// Setting Bounds of a Frame.
f.setBounds( 200 , 200 , 400 , 300 );
// Setting Resizable status of frame as false
f.setResizable( false );
// Setting Visible status of frame as true.
f.setVisible( true );
}
} |
Output :
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