Java/Swing: Obtain Window/JFrame from inside a JPa

问题:

How can I get the JFrame in which a JPanel is living?

My current solution is to ask the panel for it's parent (and so on) until I find a Window:

Container parent = this; // this is a JPanel
do {
    parent = parent.getParent();
} while (!(parent instanceof Window) && parent != null);
if (parent != null) {
    // found a parent Window
}

Is there a more elegant way, a method in the Standard Library may be?

回答1:

You could use SwingUtilities.getWindowAncestor(...) method that will return a Window that you could cast to your top level type.

JFrame topFrame = (JFrame) SwingUtilities.getWindowAncestor(this);

回答2:

There are 2 direct, different methods for this in SwingUtilities which provide the same functionality (as noted in their Javadoc). They return java.awt.Window but if you added your panel to a JFrame, you can safely cast it to JFrame.

The 2 direct and most simple ways:

JFrame f1 = (JFrame) SwingUtilities.windowForComponent(comp);
JFrame f2 = (JFrame) SwingUtilities.getWindowAncestor(comp);

For completeness some other ways:

JFrame f3 = (JFrame) SwingUtilities.getAncestorOfClass(JFrame.class, comp);
JFrame f4 = (JFrame) SwingUtilities.getRoot(comp);
JFrame f5 = (JFrame) SwingUtilities.getRootPane(comp).getParent();

回答3:

JFrame frame = (JFrame)SwingUtilities.getRoot(x);

回答4:

As other commentators already mentioned it is not generally valid to simply cast to JFrame. That does work in most special cases, but I think the only correct answer is f3 by icza in https://stackoverflow.com/a/25137298/1184842

JFrame f3 = (JFrame) SwingUtilities.getAncestorOfClass(JFrame.class, comp);

because this is a valid and safe cast and nearly as simple as all other answers.