JavaFX：为什么带有JComponent参数的SwingNode的setContent方法不能接受JPanel？

Question

I have the following code:

private void launchSingleRecordWindow() {
    SwingNode swingNode = new SwingNode();
    MainStageController.setContent(new AnchorPane(swingNode));
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            JPanel webcamPanel = new WebcamPanel(selectedWebcam);
            swingNode.setContent(webcamPanel);
        }
    });
}

But to my surprise the string swingNode.setContent(webcamPanel); isn't correct.

IntelliJ IDEA says:

java: incompatible types: javax.swing.JPanel cannot be converted to javax.swing.JComponent .

I've tried to make separate class, but it works only when it is a subclass of JComponent , but not for its subclasses, such as JFrame or JPanel . What is wrong?

Answer 1

It's telling you that a JFrame is not a JComponent . Guess what? It's right.

See for yourself: JFrame API

Answer 2

JFrame不是JComponent子类，它是Component子类，因此无法将其转换为JComponent

Answer 3

The error is strange:

java: incompatible types: javax.swing.JPanel cannot be converted to javax.swing.JComponent

Because ... A JPanel is a JComponent:

Class JPanel
java.lang.Object
   java.awt.Component
      java.awt.Container
         javax.swing.JComponent
            javax.swing.JPanel

And a SwingNode does accept a JComponent:

public void setContent(javax.swing.JComponent content)

So ... it should work to pass a JPanel to a SwingNode::setContent

Check your code or compile in verbose mode and see if the error is what you think it is!