Check JTextField validity when Focuslost.

Question

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class Frame1 extends JFrame {
JTextField jTextField1 = new JTextField();
JButton jButton1 = new JButton();
public Frame1() {
try {
jbInit();
catch(Exception e) {
e.printStackTrace();
public static void main(String[] args) {
Frame1 frame1 = new Frame1();
frame1.setSize(500,500);
frame1.setVisible(true);
private void jbInit() throws Exception {
jTextField1.setBounds(new Rectangle(38, 168, 150, 26));
jTextField1.addFocusListener(new java.awt.event.FocusAdapter() {
public void focusLost(FocusEvent e) {
jTextField1_focusLost(e);
this.getContentPane().setLayout(null);
jButton1.setBounds(new Rectangle(229, 169, 101, 27));
jButton1.setText("jButton1");
this.getContentPane().add(jTextField1, null);
this.getContentPane().add(jButton1, null);
Hi All
I need to verify whether JTextField is empty or not and if it is empty I need to show dialog box and focus into JTextField once again.
I tried with following code. But end up with endless loop.
Please advice me.
BR
Senaka
void jTextField1_focusLost(FocusEvent e) {
Date dateEnd = new Date();
if(jTextField1.getText().equals("")) {
     JOptionPane.showMessageDialog(
this,
"Error",
"Error",
JOptionPane.ERROR_MESSAGE);
     jTextField1.requestFocus();
}else {
}

Answer 1

the problem is that you are calling the function on focuslost, when u click on the button, the field loses focus and so the loop goes on to infinite, instead use Actionevent, i have attached this code, try and let me know
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class Frame1 extends JFrame {
JTextField jTextField1 = new JTextField();
JButton jButton1 = new JButton();
public Frame1() {
try {
jbInit();
catch(Exception e) {
e.printStackTrace();
public static void main(String[] args) {
Frame1 frame1 = new Frame1();
frame1.setSize(500,500);
frame1.setVisible(true);
private void jbInit() throws Exception {
jTextField1.setBounds(new Rectangle(38, 168, 150, 26));
this.getContentPane().setLayout(null);
jButton1.setBounds(new Rectangle(229, 169, 101, 27));
jButton1.setText("jButton1");
jButton1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
     jTextField1_focusLost();
this.getContentPane().add(jTextField1, null);
this.getContentPane().add(jButton1, null);
void jTextField1_focusLost() {
Date dateEnd = new Date();
if(jTextField1.getText().equals("")) {
JOptionPane.showMessageDialog(null,"Field Empty");
else {
JOptionPane.showMessageDialog(null,"Yes Field has text");
any problems just give a shout :)
enjoy!!