Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.FlowLayout;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.text.JTextComponent;

public class Main {
    public static void main(String[] argv) throws Exception {
        JTextField component = new JTextField(10);
        JTextField component1 = new JTextField(10);
        component.addFocusListener(new MyFocusListener());
        component1.addFocusListener(new MyFocusListener());
        JFrame f = new JFrame();
        f.setLayout(new FlowLayout());
        f.add(component1);
        f.add(component);
        f.pack();
        f.setVisible(true);

    }
}

class MyFocusListener extends FocusAdapter {
    boolean showingDialog = false;

    public void focusGained(FocusEvent evt) {
        final JTextComponent c = (JTextComponent) evt.getSource();
        String s = c.getText();

        for (int i = 0; i < s.length(); i++) {
            if (!Character.isDigit(s.charAt(i))) {
                c.setSelectionStart(i);
                c.setSelectionEnd(i);
                break;
            }
        }
    }

    public void focusLost(FocusEvent evt) {
        final JTextComponent c = (JTextComponent) evt.getSource();
        String s = c.getText();

        if (evt.isTemporary()) {
            return;
        }
        for (int i = 0; i < s.length(); i++) {
            if (!Character.isDigit(s.charAt(i))) {
                System.out.println("must only contain digits");
                c.requestFocus();
                break;
            }
        }
    }
}