How to constrain JFileChooser to select particular number files?

问题

Using JFileChooser, I have enabled multi-selection mode by setMultiSelectionEnabled(true), but how can I set a limit so that the user can only select a particular number of text (or other) files?

public File[] fileSelect() {
    fileChooser = new JFileChooser();
    fileNameExtFilter = new FileNameExtensionFilter("Text File","txt");
    fileChooser.setCurrentDirectory(new java.io.File("."));
    fileChooser.setDialogTitle("Open Question Set");
    fileChooser.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);
    fileChooser.setAcceptAllFileFilterUsed(false);
    fileChooser.setFileFilter(fileNameExtFilter);
    fileChooser.setMultiSelectionEnabled(true);

    if (fileChooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION)
        return fileChooser.getSelectedFiles();
    else
        return null;
}

回答1:

Several approaches are possible:

• Create a custom FileChooserUI by subclassing BasicFileChooserUI and limit the selection in your implementation of the nested class SelectionListener.

• Create a custom file browser, as shown here, and limit the selection in the relevant listener.

• Use the existing FileChooser and present a dialog when the selection exceeds three; consider using a JTable containing checkboxes as shown here.

• Use separate chooser panels, as shown here for two files via createPathPanel().

The best choice and exact details will depend on the use case.

来源：https://stackoverflow.com/questions/32523630/how-to-constrain-jfilechooser-to-select-particular-number-files