killisrinivas
asked on
Why getContentPane() ??
Why getContentPane() for the Swing components to be added to the frame? Why can't we simply add the components directly like in the case of AWT components? The method returns Container object instead of JComponent which is the super class of all Swing Components. WHY?
regards,
killi
regards,
killi
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> most swing components would not let you to add something
any examples ?
any examples ?
Hi,
heyhey_, thank you a lot! It was funny to know about...
I thought it's a crazy idea to call JButton.add(). I was wrong. JButton appears to have FlowLayout inside and adds components. JTextArea appears to have null layout, but still adds components. Don't know what JComboBox does to component I trying to add. Let's say that in general result of JComponent.add() is undefined.
I still feel that most JComonents are not supposed to contain other components, that's why Container looks like a better hint... It was really fun to find that JComponent subclasses Container when I was learning swing.
Igor.
heyhey_, thank you a lot! It was funny to know about...
I thought it's a crazy idea to call JButton.add(). I was wrong. JButton appears to have FlowLayout inside and adds components. JTextArea appears to have null layout, but still adds components. Don't know what JComboBox does to component I trying to add. Let's say that in general result of JComponent.add() is undefined.
I still feel that most JComonents are not supposed to contain other components, that's why Container looks like a better hint... It was really fun to find that JComponent subclasses Container when I was learning swing.
Igor.
I agree :)
but " ... not supposed to contain ... " is quite different than " ... would not let you to add something ... "
JLabel is pretty good container if you want to add background Image btw.
re ContentPane - you can set your own ContentPane which is Container, but not JComponent
but " ... not supposed to contain ... " is quite different than " ... would not let you to add something ... "
JLabel is pretty good container if you want to add background Image btw.
re ContentPane - you can set your own ContentPane which is Container, but not JComponent
> JButton appears to have FlowLayout inside
you can always change the layout.
you can always change the layout.
The method returns Container object instead of JComponent which is the super class of all Swing Components. WHY?
Because in case you want to set ur own ContentPane, you might want to use, say, CellRendererPane, which is not derived from JComponent. JComponent implements some functionalities a content pane doesn't need, that's why you rather use its subclass.
If I asked what it takes to make a forest, you'd say 'trees', not 'oaks'. Same thing here.
Because in case you want to set ur own ContentPane, you might want to use, say, CellRendererPane, which is not derived from JComponent. JComponent implements some functionalities a content pane doesn't need, that's why you rather use its subclass.
If I asked what it takes to make a forest, you'd say 'trees', not 'oaks'. Same thing here.
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No comment has been added lately, so it's time to clean up this TA.
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I will leave a recommendation in the Cleanup topic area that this question is:
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OK by me if everyone else agrees (or declines to comment).
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per recommendation
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Thanks :-)
My speculation about Container use:
While JComponent is subclass of Container, most swing components would not let you to add something to them. So, use of Container instead of JComponent is a hint that you can add components there.
As for add(), I don't understand why can't it be shortcut to getContentPane().add(). But the only thing we can do is use JFrame in a way it's supposed to be used.
Regards,
Igor Bazarny,
Brainbench MVP for Java 1
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