verifiersample.java

The Definitive Guide to Java Swing, Third Edition by John Zukowski (Author) 源码

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

public class VerifierSample {
  public static void main(String args[]) {
    Runnable runner = new Runnable() {
      public void run() {
        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);
      }
    };
    EventQueue.invokeLater(runner);
  }
}