Java: JFrame.setLocationRelativeTo(null) not centering the window on Ubuntu 10.04 / gnome 2.30.2 with OpenJDK 1.6.0_18

Question

Sample code:

    JFrame jFrame = new JFrame("Test");
    jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jFrame.setLocationRelativeTo(null);
    jFrame.setSize(600, 600);
    jFrame.pack();
    // jFrame.setLocationRelativeTo(null); // same results
    jFrame.setVisible(true);

Is this the OpenJDK's fault? I recall hearing it wasn't as good as Sun's, but since it became the standard for Ubuntu or whatever I decided to go along with it. The program is probably gonna run on windows, so I suppose I'm gonna have to check there... Any easy way to fix this in a platform independent way without breaking it where it already works?

In you screenshot, the top-left corner is perfectly centered. You just need to offset it by the height and width of the frame. — jjnguy, Aug 13 '10 at 19:36
As pointed out by Evan, this code is calling setLocationRelativeTo() too early in the code. It must be done **after** pack()/setSize(). Also note that in both your example and Evan's, the call to setSize() is redundant if immediately followed by pack(). — Andrew Thompson, Mar 18 '11 at 12:25

score 22 · Answer 1 · answered Mar 18 '11 at 11:55

22

JFrame jFrame = new JFrame("Test");
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//jFrame.setLocationRelativeTo(null);
jFrame.setSize(600, 600);
jFrame.pack();
jFrame.setVisible(true);
jFrame.setLocationRelativeTo(null); //To center the code

This will correct the problem and center the Jframe

answered Mar 18 '11 at 11:55

Evan

296
3
4

8

Basically, call pack() before setLocationRelativeTo(). This is because pack() computes the size of the window, which is required to perform the centering calculation correctly. – Greg Mattes Jan 22 '13 at 16:38

jjnguy · Accepted Answer · 2010-08-13T19:53:29.293

5

One way is to manually position the window. Put the following code right after your call to pack().

Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Point middle = new Point(screenSize.width / 2, screenSize.height / 2);
Point newLocation = new Point(middle.x - (jFrame.getWidth() / 2), 
                              middle.y - (jFrame.getHeight() / 2));
jFrame.setLocation(newLocation);

Disclaimer, this was only tested on windows.

Also, you should always use setPreferredSize() instead of setSize().

edited Aug 13 '10 at 19:53

answered Aug 13 '10 at 19:33

jjnguy

136,852
53
295
323

@captain, you get the same results as in your question? – jjnguy Aug 13 '10 at 19:37
@captain, try running it without dividing getWidth and getHeight by 2. So: `new Point(middle.x - (jFrame.getWidth()), middle.y - (jFrame.getHeight()));` – jjnguy Aug 13 '10 at 19:41
@Justin same thing happened. It's weird because I can set the location normally, but neither of those methods worked. Well, I realize that the problem is the jFrame getWidth() and getHeight(). Width is 10, Height is 30, even though I've set the jframe size to 600 x 600. – captain poop Aug 13 '10 at 19:45
@captain, what do you mean by "set the location normally'? – jjnguy Aug 13 '10 at 19:46
@cap, also, use `setPreferredSize()` instead of `setSize()` – jjnguy Aug 13 '10 at 19:47
@Justin: aha! the problem was setSize(). I had to use setPreferredSize(). Thanks! – captain poop Aug 13 '10 at 19:49

YoannFleuryDev · Answer 3 · 2013-10-07T20:51:42.427

4

Just a precision : If you set the location before the size of the frame, you will center the top left corner of the window because the size is (0,0). You have to set the size before the location.

JFrame jFrame = new JFrame("Test");
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setSize(600, 600);
jFrame.pack();
jFrame.setLocationRelativeTo(null);
jFrame.setVisible(true);

It works well with me with OpenJDK-6 and Ubuntu 13.04. Try it on other platforms.

edited Oct 07 '13 at 20:51

answered Oct 03 '13 at 17:00

YoannFleuryDev

914
1
12
22

Welcome to SO! Can you please expand your answer with a code sample? – Brian Oct 03 '13 at 17:19
1

Thanks. Yes, of course, I'll edit my answer. (Sorry for my English, I'm a French student in computer science). – YoannFleuryDev Oct 07 '13 at 20:55

score 3 · Answer 4 · edited Nov 06 '11 at 02:04

3

jFrame.validate();

This actually works better since pack can change the frame size, while validate leaves the frame size alone.

edited Nov 06 '11 at 02:04

chown

51,908
16
134
170

answered Nov 05 '11 at 19:36

Nicholas Duchon

31
1

score 2 · Answer 5 · answered May 09 '13 at 20:05

2

I know this is an old question, but setLocationRelativeTo() will work but it must be called after pack(). Frame's getWidth() and getHeight() return different (correct) values after packing and that's why OP is unable to center.

answered May 09 '13 at 20:05

mrazjava

21
1
1

score 1 · Answer 6 · answered Jul 06 '18 at 10:57

Just set the size before setting the location.

Wrong:

jFrame.setLocationRelativeTo(null);
jFrame.setSize(600, 600);

Correct:

jFrame.setSize(600, 600);
jFrame.setLocationRelativeTo(null);

Note: Call setVisible() at last to prevent "jumping" of the window.

score 0 · Answer 7 · answered Jan 09 '14 at 04:00

You should not declare the jFrame size before giving the relative location. If you do that what happens is that will draw your iFrame away from the given location.

This is wrong----

JFrame jFrame = new JFrame("Test");
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setLocationRelativeTo(null);
jFrame.setSize(600, 600);
jFrame.pack();
jFrame.setVisible(true);

This is right----

JFrame jFrame = new JFrame("Test");
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//size comes first
jFrame.setSize(600, 600);

//and then the position
jFrame.setLocationRelativeTo(null);

jFrame.pack();
jFrame.setVisible(true);

In your comments you said size comes first then you pack the `JFrame` after `setLocationRelativeTo`... — Dan, Aug 17 '17 at 06:27

Java: JFrame.setLocationRelativeTo(null) not centering the window on Ubuntu 10.04 / gnome 2.30.2 with OpenJDK 1.6.0_18

7 Answers7

Linked