カウントアップしていく

MyFrame.java

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

public class MyFrame extends JFrame {
    public static void main(String[] args) {
        new MyFrame().setVisible(true);
    }

    JTextArea text = new JTextArea();
    MyThread thread = new MyThread();

    MyFrame() {
        setSize(100, 100);
        setLayout(new BorderLayout());
        add(text, BorderLayout.CENTER);
        thread.start();
    }

    class MyThread extends Thread {

        public void run() {
            int count = 0;
            while (true) {
                synchronized (this) {
                    try {
                        this.wait(1000);
                    } catch (InterruptedException ignore) {
                    }
                }
                count++;
                text.append(count + "\n");
                System.out.println(count);
            }
        }
    }
}