Hi

Now, use the code and get the answer.

import javax.swing.*;

public class DemoTryCatchDialog{
public static void main(String args[]){
String str_value;
boolean number;
int num;
do{
str_value = JOptionPane.showInputDialog(null, "Please input an integer value");
number = true;
try{
num = Integer.parseInt(str_value);
JOptionPane.showMessageDialog(null, "You entered number is: " + num);
}
catch(NumberFormatException e){
JOptionPane.showMessageDialog(null, "You did not enter a valid number");
number = false;
}
}
while(!number);
}
}

d

This can be done using KeyEvent

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.JOptionPane;

class GUIExample1 extends JFrame implements ActionListener
{
JLabel numberLabel;
JTextField numberTextField;
JButton displayButton;
public GUIExample1()
{
Container pane = getContentPane();
pane.setLayout(new FlowLayout());
numberLabel = new JLabel("Enter a number:");
numberTextField = new JTextField(4);
//calling the KeyEvent method
numberTextField.addKeyListener(new KeyAdapter(){
public void keyTyped(KeyEvent evt){
numberTextField_KeyTyped(evt);
}
});
displayButton = new JButton("Enter");
pane.add(numberLabel);
pane.add(numberTextField);
pane.add(displayButton);
displayButton.addActionListener(this);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("GUI Example");
pack();
show();
}
public void actionPerformed(ActionEvent event)
{
Object source = event.getSource();
if (source == displayButton)
{
double result = Integer.parseInt(numberTextField.getText());
JOptionPane.showMessageDialog(null, "you entered " + (int)(result), "Hello", JOptionPane.PLAIN_MESSAGE);
System.exit(0);
}
}

//added newly ----- KeyEvent
public void numberTextField_KeyTyped(KeyEvent evt)
{
try{
char dotChar=evt.getKeyChar();
int dot=(int)dotChar;
char c = evt.getKeyChar(); //character object to hold the typed character
if (!(Character.isDigit(c)))
{
getToolkit().beep();
evt.consume();
JOptionPane.showMessageDialog(this,"characters are not allowed");
numberTextField.requestFocus(true);

}
}
catch(Exception e){
System.out.println("---error in validation---"+e);
}
}//end of the method

public static void main(String[] args)
{
new GUIExample1();
}
}

This will work fine.. Try it

Thanks