Java: mytextarea.setText(“hello”) + Thread.sleep(1000) = strange result

Question

I have something like this:

for(int i=0; i<5; i++){
    mytextarea.setText(\"hello \" + i);
    try{
        Thread.currentThread().sleep(1000); //to give         


        

Answer 1

Another way to not block the Event Dispatch Thread (EDT) is to start a new Thread:

Thread thread = new Thread(new Runnable() {
    @Override
    public void runt() {
        for (int i=0; i<5; i++) {
            mytextarea.setText("hello " + i);
            try {
                Thread.sleep(1000); //to give time for users to read
            } catch (InterruptedException e) {
                break;    // interrupt the for
            }
        }
    }
});
thread.start();

EDIT:
In general Swing is NOT thread safe, that is, Swing methods not marked as thread safe should only be called on the EDT. setText() is thread-safe, so it's no problem in the above code.

To run a code on the EDT, you use invokeAndWait() or invokeLater() from javax.swing.SwingUtilities (or from java.awt.EventQueue).

For more details see: Swing's Threading Policy