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How to make a JFrame Modal in Swing java
I have 2 JFrames one is the main JFrame and the other one is a sub JFrame, and I'm trying to make the main JFrame inaccessible to user interactions when I display the sub JFrame.
How to make a modal JFrame?
Don't. Use a modal JDialog -- that's precisely what they're for. You understand of course that a JDialog can hold a complex GUI, as complex as any held by a JFrame.
We often run into posts like these by folks who use a GUI-builder such as NetBeans to help them create their GUI's, and since the second window's code was created by the builder to extend a JFrame, it's very hard for the programmer to go back and change it to a dialog. The way to fix this is to try to gear your Swing code creation towards creation of JPanels, not top-level windows such as JFrames. This way you could use the created JPanel in a JFrame if desired, a JDialog if desired, a JApplet, or even another JPanel, whatever works best for the situation. This will increase your code's flexibility tremendously.
use JDialog and send the third parameter to its constructor as true (modal)
来源：https://stackoverflow.com/questions/8351505/how-to-make-a-modal-jframe