Customizing JPopupMenu in JFileChooser: accessing internal components

Customizing JPopupMenu in JFileChooser is a method that allows us to access internal components. This way we can add a custom popup menu to the file selection dialog and be able to operate on the internal components. This technique is very useful when dealing with specific needs, such as adding additional function buttons or modifying the default menu items. In this article, PHP editor Xinyi will introduce how to access the internal components of JFileChooser by customizing JPopupMenu to achieve a more flexible and personalized file selection function. Let’s take a look!

Question content

How to access the JPopupMenu called from JFileChooser and customize it (background, foreground, border)? The problem is that the popup is created inside sun.swing.FilePane and I cannot access it because sun.* packages are not accessible by default. Developing a new FileChooser is not feasible because a lot of work has already been done. Do you have any ideas?

I tried iterating over the nested components but that produced no results since FilePane could not be imported.

Solution

sun.swing.filepane extends jpanel, you can search this jpanel and get jpopupmenu.

import java.awt.*;
import java.util.Objects;
import java.util.stream.Stream;
import javax.swing.*;

public class FileChooserPopupMenuTest {
  public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
      JFileChooser chooser = new JFileChooser();
      descendants(chooser)
          .filter(JPanel.class::isInstance)
          .map(c -> ((JPanel) c).getComponentPopupMenu())
          .filter(Objects::nonNull)
          .findFirst()
          .ifPresent(popup -> {
            popup.addSeparator();
            popup.add(new JCheckBoxMenuItem("JCheckBoxMenuItem"));
          });
      chooser.showOpenDialog(null);
    });
  }

  public static Stream<Component> descendants(Container parent) {
    return Stream.of(parent.getComponents())
        .filter(Container.class::isInstance)
        .map(Container.class::cast)
        .flatMap(c -> Stream.concat(Stream.of(c), descendants(c)));
  }
}

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