[platform-swt-dev] about swt thread.

[Shan <jiangwen.huang@xxxxxxxxx>]

Hi,

 

I have a problem about swt thread. please see below code.

Press button two to create a thread, and let it refresh button one's text.

But I press button two again, and want to stop the refresh action.

It seems that I have lost the widget's control.

 

According to eclipse platform api, the caller of asyncExec() method and

the new thread are parallel. So when the new thread is running, I can do

some operation. How to resolve?

 

Thanks. 

 

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Rectangle ;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

 

public class Test {
    Display display = new Display();
    Shell shell = new Shell(display);
    Button buttonOne = new Button(shell, SWT.PUSH );
    Button buttonTwo = new Button(shell, SWT.PUSH);
   
    static volatile boolean isRunning = false;

 

    public Test() {
        shell.setText("Test");
        shell.setSize(200, 100);
       
        Rectangle clientArea = shell.getClientArea ();
       
        buttonOne.setText("Test Only");
        buttonOne.setBounds(clientArea.x, clientArea.y,
                            clientArea.width, clientArea.height / 2);
       
        buttonTwo.setText("Start");
        buttonTwo.setBounds(clientArea.x, clientArea.y + clientArea.height / 2,
                            clientArea.width, clientArea.height / 2);
        buttonTwo.addSelectionListener (new SelectionAdapter() {
            public void widgetSelected(SelectionEvent e) {  
                if (isRunning)
                    buttonTwo.setText("Sart");
                else
                    buttonTwo.setText("Stop");               
                isRunning = !isRunning;
               
                getTask(buttonOne).start();
            }
        });
       
        shell.open ();
       
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }

 

    public static void main(String[] args) {
        System.out.println("start is running : " + isRunning);
        new Test();       
    } 

 

    public Thread getTask(Button button) {
        final Button theButton = button;
       
        return new Thread() {   
            public void run() {               
                display.asyncExec(new Runnable() {
                    public void run() {
                        int i;
                        while (isRunning)
                        {
                            i = (int) (Math.random() * 10000);
                            theButton.setText("Get num : " + i);
                           
                            try {
                                Thread.sleep(500);
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                });
            }
        };
    }
}