Visual suspend and resume
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class SwingSuspendResume extends JPanel implements Runnable {
private static final String[] symbolList = { "|", "/", "-", "\\", "|", "/",
"-", "\\" };
private Thread runThread;
private JTextField symbolTF;
public SwingSuspendResume() {
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() {
public void actionPerformed(ActionEvent e) {
suspendNow();
}
});
resumeB.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
resumeNow();
}
});
JPanel innerStackP = new JPanel();
innerStackP.setLayout(new GridLayout(0, 1, 3, 3));
innerStackP.add(symbolTF);
innerStackP.add(suspendB);
innerStackP.add(resumeB);
this.setLayout(new FlowLayout(FlowLayout.CENTER));
this.add(innerStackP);
}
private void suspendNow() {
if (runThread != null) { // avoid NullPointerException
runThread.suspend();
}
}
private void resumeNow() {
if (runThread != null) { // avoid NullPointerException
runThread.resume();
}
}
public void run() {
try {
// Store this for the suspendNow() and
// resumeNow() methods to use.
runThread = Thread.currentThread();
int count = 0;
while (true) {
// each time through, show the next symbol
symbolTF.setText(symbolList[count % symbolList.length]);
Thread.sleep(200);
count++;
}
} catch (InterruptedException x) {
// ignore
} finally {
// make sure that the reference to it is also lost.
runThread = null;
}
}
public static void main(String[] args) {
SwingSuspendResume vsr = new SwingSuspendResume();
Thread t = new Thread(vsr);
t.start();
JFrame f = new JFrame();
f.setContentPane(vsr);
f.setSize(320, 200);
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
}
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