How to activate window in Java?

Question

I would like to activate my Swing application programatically. I mean that I would like to write code that cause the JFrame to be visible and focused (the window header should be highlighted). I tried to use requestFocus(). It works only if application has at least 2 windows A and B: A is hidden, B is visible. Now if I call A.requestFocus() it becomes active as I want. It does not happen if application has only one window or if both windows are invisible.

I found 2 workarounds. 1. use fake transparent undecorated frame that is always on top. This fake window will play role of window B. I did not try to implement it but it seems that it should work. 2. call A.setAlwaysOnTop(true). This brings window A on top of other windows. But it is not in focus yet. Use java.awt.Robot (mouseMove, mousePress, mouseRelease) to make a click on the header of window A. Now call A.setAlwaysOnTop(false) and return mouse pointer back to its previous position. I implemented the code and it works but it looks like an ugly workaround.

Is there a "right" solution?

Answer 1

This should do it:

frame.setSelected(true);

and you probably want it inside a try/catch block...

If that doesn't work on the OS you're using, there are two more possibilities:

frame.setAlwaysOnTop(true);
frame.setAlwaysOnTop(false);

and

frame.setVisible(true);
frame.setVisible(true); // Yes you need this second one

Answer 2

frame.setState(Frame.NORMAL); // restores minimized windows
frame.toFront(); // brings to front without needing to setAlwaysOnTop
frame.requestFocus();

for everything you could want to know in excruciating detail, see this page: http://www.developer.com/java/other/article.php/3502181/Window-Focus-and-State-in-Java.htm