MainClass.java Source code

Introduction

Here is the source code for MainClass.java

Source

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.InputVerifier;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;

public class MainClass {
    public static void main(String args[]) throws Exception {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JTextField nameTextField = new JTextField();
        frame.add(nameTextField, BorderLayout.NORTH);
        frame.add(new JTextField(), BorderLayout.SOUTH);

        InputVerifier verifier = new InputVerifier() {
            public boolean verify(JComponent input) {
                final JTextComponent source = (JTextComponent) input;
                String text = source.getText();
                if ((text.length() != 0) && !(text.equals("Exit"))) {
                    JOptionPane.showMessageDialog(source, "Can't leave.", "Error Dialog",
                            JOptionPane.ERROR_MESSAGE);
                    return false;
                } else {
                    return true;
                }
            }
        };
        nameTextField.setInputVerifier(verifier);

        frame.setSize(250, 100);
        frame.setVisible(true);
    }
}