Re: merging two independant Java programs into one Java program running
two threads?
On 10/27/2014 06:33, John wrote:
Hi:
I have two independent Java programs. Program A is a GUI program.
Program B continuously take screen shots every 5 seconds and save
them into PNG picture files.
Right now, I start running Java Program B first, then start Program
A, doing GUI interaction etc.
I hope to merge the two into one Java program which runs the original
two programs by two interdependent processes or threads(not sure
which one is correct. Help please). And I would like to have this
feature: when GUI interaction by me proceeds to certain stage, e.g.
when I click Button 'XYZ' on the GUI, the process/thread taking
screen shots halts. After a while, when I click another button, the
halted process/thread proceeds again. At the end, when I quit the GUI
program, the process/thread taking the screen shots ends as well.
I think this makes me learn multi-thread programming or inter-process
communication. If you could shed some light on this project, I would
greatly appreciate it.
Thank you very much.
Eric gave you a good discussion of the issues. This is just a simple
example of starting and stopping a Thread to do a second task in your
GUI program.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class test2 extends JFrame implements ActionListener, Runnable {
private final JMenuItem startstop;
private final JTextArea textArea;
private volatile Thread thread;
private boolean runFlag;
public test2() {
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent we) {
stop();
dispose();
}
});
JMenuBar mb = new JMenuBar();
setJMenuBar(mb);
JMenu file = mb.add(new JMenu("file"));
startstop = file.add("start");
startstop.addActionListener(this);
textArea = new JTextArea("");
JScrollPane scrollPane = new JScrollPane(textArea);
add(scrollPane,BorderLayout.CENTER);
setSize(400,300);
setLocationRelativeTo(null);
setVisible(true);
}
public void actionPerformed(ActionEvent ae) {
switch (ae.getActionCommand()) {
case "start":
textArea.append("start\n");
startstop.setText("stop");
start();
break;
case "stop":
textArea.append("stop\n");
startstop.setText("start");
stop();
break;
}
}
public void start() {
runFlag = true;
thread = new Thread(this);
thread.start();
}
public void run() {
while (runFlag) {
// do your thing
EventQueue.invokeLater(new Runnable() {
public void run() {
textArea.append("running\n");
}
});
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
EventQueue.invokeLater(new Runnable() {
public void run() {
textArea.append("sleep interrupted\n");
}
});
}
}
}
public void stop() {
runFlag = false;
thread.interrupt();
}
public static void main(String... args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new test2();
}
});
}
}
--
Knute Johnson