Java by API/javax.swing/InputVerifier

implements InputVerifier

   <source lang="java">

import java.awt.BorderLayout; import javax.swing.InputVerifier; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JTextField; public class MainClass {

 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();
   JTextField textField3 = 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);
   textField3.setInputVerifier(verifier);
   frame.add(textField1, BorderLayout.NORTH);
   frame.add(textField2, BorderLayout.CENTER);
   frame.add(textField3, BorderLayout.SOUTH);
   frame.setSize(300, 100);
   frame.setVisible(true);
 }

}

      </source>