import java.awt.BorderLayout; import javax.swing.InputVerifier; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JTextField; public class VerifierSample { public static void main(String args[]) { JFrame frame = new JFrame("Verifier Sample"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JTextField textField1 = new JTextField(); JTextField textField2 = new JTextField(); InputVerifier verifier = new InputVerifier() { public boolean verify(JComponent comp) { boolean returnValue; JTextField textField = (JTextField) comp; try { Integer.parseInt(textField.getText()); returnValue = true; } catch (NumberFormatException e) { returnValue = false; } return returnValue; } }; textField1.setInputVerifier(verifier); frame.add(textField1, BorderLayout.NORTH); frame.add(textField2, BorderLayout.CENTER); frame.setSize(300, 100); frame.setVisible(true); } }