public class Demo extends JFrame {

    private Thread thread;//定义线程

    final JProgressBar progressBar = new JProgressBar();//进度条

    public Demo() {

        setBounds(100, 100, 200, 100);

        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        getContentPane().add(progressBar, BorderLayout.NORTH);

        progressBar.setStringPainted(true);//显示数字

//使用匿名内部类实现线程对象

        thread = new Thread() {

            int count = 0;//进度数据

            public void run() {

                while (true) {//无限循环，一般在不知道循环次数时使用

                    progressBar.setValue(++count);

                    if (count == 20) {

                        //thread.interrupt();//如果thread=new Thread(new Runnalbe{...}),this无效

                        this.interrupt();//this指代Thread()

                    }

                    try {

                        Thread.sleep(100);//休眠0.1s

                    } catch (InterruptedException e) {

                        e.printStackTrace();

                        System.out.println("20%处被中断");//抛出异常

                        break;//一定要有break，否则无法中断

                    }

                }

            }

        };

        thread.start();

        setVisible(true);

    }

    public static void main(String[] args) {

        new Demo();

    }

}