Thread suspend()挂起resume()恢复

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

public class ThreadVSR extends JPanel implements Runnable{
    private static final String[] symbolList={"|","/","--","\","/","--","\"};
    private Thread runThread;
    private JTextField symbolTF;

    public ThreadVSR() {
        symbolTF=new JTextField();
        symbolTF.setEditable(false);
        symbolTF.setFont(new Font("Monospaced",Font.BOLD,26));
        symbolTF.setHorizontalAlignment(JTextField.CENTER);
        final JButton suspendB=new JButton("suspend");
        final JButton resumeB=new JButton("resume");
        suspendB.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                suspendNow();
            }
        });
        resumeB.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                resumeNow();
            }
        });
        JPanel in=new JPanel();
        in.setLayout(new GridLayout(0,1,3,3));
        in.add(symbolTF);
        in.add(suspendB);
        in.add(resumeB);
        this.setLayout(new FlowLayout(FlowLayout.CENTER));
        this.add(in);
    }
    private void suspendNow(){
        if (this.runThread!=null){
            runThread.suspend();
        }
    }
    private void resumeNow(){
        if (this.runThread!=null){
            this.runThread.resume();
        }
    }

    @Override
    public void run() {
        try {
            runThread=Thread.currentThread();
            int count=0;
            while (true){
                symbolTF.setText(symbolList[count%symbolList.length]);
                Thread.sleep(200);
                count++;
                System.out.println(count);
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        runThread=null;
    }
    public static void main(String[] args){
        ThreadVSR vrs=new ThreadVSR();
        Thread t=new Thread(vrs);
        t.start();
        JFrame f=new JFrame("suspend-resume-");
        f.setContentPane(vrs);
        f.setSize(320,200);
        f.setVisible(true);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}