revalidate vs repaint in Java Swing

Question

Can someone tell me which one do I use revalidate() or repaint(), if I want to replace the contents of a JPanel.

I tried using removeAll(), then adding my new content, then calling revalidate(). But it's not working. However, If I add a call to repaint() in addition to revalidate(), then it works fine. It's confusing me. Can someone help?

Answer 1

You need to call repaint() and revalidate() both in order to replace all the elements from your JPanel.

• repaint(): This method tells Swing that an area of the window is dirty.
• revalidate(): This method tells the layout manager to recalculate the layout that is necessary when adding components. 

Due to this, the children of the panel are repainted.

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