This week's giveaway is in the Android forum.
We're giving away four copies of Android Security Essentials Live Lessons and have Godfrey Nolan on-line!
See this thread for details.
The moose likes Swing / AWT / SWT and the fly likes The purpose of using getContentPane() Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login

Win a copy of Android Security Essentials Live Lessons this week in the Android forum!
JavaRanch » Java Forums » Java » Swing / AWT / SWT
Bookmark "The purpose of using getContentPane()" Watch "The purpose of using getContentPane()" New topic

The purpose of using getContentPane()

Griff Haldeman

Joined: Jul 01, 2011
Posts: 5
What's the point of calling frame.getContentPane().add(button) when frame.add(button) works all the same? To my understanding, adding directly to the frame without first getting the content pane is disparaged, but if someone could elaborate on this, it'd be great.
Greg Charles

Joined: Oct 01, 2001
Posts: 2840

It's been awhile since I used Swing, but if I remember right, JFrame has an addImpl() method that adds components to the content pane by default. That's why frame.getContentPane.add(...) does the same thing as frame.add(...). As to why or if that's a bad practice, I'm not sure. Probably because you're not being explicit about what you're doing. There's a glass pane, where you can draw things that appear superimposed over what's in the content pane. Also a root pane and layered pane, but I forget what those do.
Griff Haldeman

Joined: Jul 01, 2011
Posts: 5
Thanks, just what I wanted to know.
Rob Spoor

Joined: Oct 27, 2005
Posts: 19655

In Java 1.4 and before, adding components to a JFrame directly, or setting its layout directly, would result in an error (of java.lang.Error or some sub class, can't remember which one it was). You really needed to use the content pane. In Java 5.0 they decided it made more sense to just redirect those calls to the content pane.

How To Ask Questions How To Answer Questions
It is sorta covered in the JavaRanch Style Guide.
subject: The purpose of using getContentPane()
Similar Threads
How to make circle?
WA #1.....word association
Can you guess what this is?
redirect, foreward
get value from radio button