Message Dialogs in Java (GUI)

Last Updated : 26 Oct, 2021

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 : 

  1. ERROR_MESSAGE
  2. WARNING_MESSAGE
  3. QUESTION_MESSAGE
  4. INFORMATION_MESSAGE

Methods Used : 

  1. 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.
  2. 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.
  3. setVisible(...): method is used to set the Visibility status of JFrame. 
    1. setVisible(true) will set JFrame visible to user.
    2. setVisible(false) will set JFrame not visible to user.
  4. 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.
  5. 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 : 

Comment
Article Tags:
Misc
Java

Explore