处理JFileChooser窗口关闭？

Question

我有一个如下所示创建的JFileChooser：

JFileChooser chooser = new JFileChooser();
int choosen = chooser.showOpenDialog(fileSelector.this);

if (choosen == JFileChooser.CANCEL_OPTION) {
  System.out.println("Closed");
}

如果我在没有做出选择的情况下关闭窗口，我会收到错误：

Exception in thread "main" java.lang.NullPointerException
    at fileSelector.fileSelector(fileSelector.java:32)
    at createAndControl.main(createAndControl.java:15)

我想知道处理这个问题的正确方法是什么，我应该在关闭窗口时调用什么操作来避免这种情况？

TIA

Answer 1

建议反过来这样做：

public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {

        @Override
        public void run() {
            JFileChooser fc = new JFileChooser();
            int returnVal = fc.showOpenDialog(null);

            if (returnVal == JFileChooser.APPROVE_OPTION) {
                File file = fc.getSelectedFile();
                //This is where a real application would open the file.
                System.out.println("Opening: " + file.getName() + ".\n");
            } else {
                System.out.println("Open command cancelled by user.\n");
            }
        }
    });
}