menuBar
is not initialized
JMenuBar menuBar = new JMenuBar();
Pergunta
I have a JMenuBar that has one menu and three JRadioButtonMenuItems
:
JMenuBar menuBar;
JMenu menu = new JMenu("Menu");
JRadioButtonMenuItem rbMenuItem;
I declare it:
menu = new JMenu("A Menu");
ButtonGroup group = new ButtonGroup();
rbMenuItem = new JRadioButtonMenuItem("A radio button menu item");
rbMenuItem.setSelected(true);
group.add(rbMenuItem);
menu.add(rbMenuItem);
menuBar.add(menu);
and I set it as the menu bar:
this.setJMenuBar(menuBar);
I run the file and it gives me:
Exception in thread "main" java.lang.NullPointerException
at geometry.tools.main.RectangleFrame.<init>(RectangleFrame.java:47)
at geometry.tools.main.RectangleFrame.main(RectangleFrame.java:95)
Java Result: 1
Line 47 is:
menuBar.add(menu);
and line 95 is:
RectangleFrame thr = new RectangleFrame();
in the:
public static void main(String[] args){
RectangleFrame thr = new RectangleFrame();
}
I don't really understand why. I haven't specified any value as null
so I don't see why I get this error.
Thanks a lot.
Solução
menuBar
is not initialized
JMenuBar menuBar = new JMenuBar();
Outras dicas
You have to create an instance of your menubar.
JMenuBar menuBar = new JMenuBar()