Update of cursor during high load
Hi All
I have a JFrame and in that Jframe I have a button. When I press that button I want to load another Jframe. Because the second JFrame takes a while to load due to different kind of operations taking place I want to set the cursor to the wait cursor.
No matter what I do, the cursor isnt updated immediately. Sometimes it will take 20 seconds before it changes. I have even put the setCursor in a thread but even take doesnt work. It seams as if Java has totally no idea how to properly balance processor power. I want the cursor to change first then startup the frame.
Has anybody got an idea how to solve this?
Martyn Hiemstra
# 1
It would help if you post some code. It sounds like you're doing something wrong but there's no way to know exactly what. Maybe this example will give you some ideas:
public class CursorTest extends JFrame {
private JButton button = new JButton("Clicky");
private Cursor waitCursor = new Cursor(Cursor.WAIT_CURSOR);
private Cursor defCursor = new Cursor(Cursor.DEFAULT_CURSOR);
public CursorTest() {
setSize(640,480);
setLocationRelativeTo(null);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent ev) {
dispose();
}
});
getContentPane().add(button, BorderLayout.NORTH);
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
new Thread() {
public void run() {
setWaitCursor();
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
setDefCursor();
}
}.start();
}
});
}
private void setWaitCursor() {
EventQueue.invokeLater(new Runnable() {
public void run() {
getGlassPane().setCursor(waitCursor);
getGlassPane().setVisible(true);
}
});
}
private void setDefCursor() {
EventQueue.invokeLater(new Runnable() {
public void run() {
getGlassPane().setCursor(defCursor);
getGlassPane().setVisible(false);
}
});
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new CursorTest().setVisible(true);
}
});
}
}
# 2
To summarize the above example, you need to use a separate Thread for the long running task otherwise the code is executed in the GUI EDT and it never gets a chance to repaint itself until the long running task finishes.
"Using Threads in Swing": http://java.sun.com/products/jfc/tsc/articles/threads/threads1.html
