如何为Java Swing Button制作ActionListener

Question

I would like to add an ActionListener that closes the BufferedWriter. Overall, my program is saving variable values to a file. These values get read into python scripts that are run in this Java GUI. However, I cannot get the (button click) ActionListener to work. I can only get a WindowListener (for frame closing) to work.

For a WindowListener I use the following code,

frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                try {
                    bufferFileWriter.close();
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }
            }

        });

For an ActionListener, which gives error: java.io.ioexception stream closed, I use the following code:

setVarFileBtn.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // Save the variable values when VarFileBtn pressed
                try {
                    bufferFileWriter.close();
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }
            }
        });

What code should I use to have a listener identify a button setVarFileBtn has been clicked, and subsequently close a BufferedWriter? Am I missing certain Java Swing code concepts in order to make the BufferedWriter write's get saved to a file?

Answer 1

I solved the problem. My error occurred because I had two ActionListener's for the same button. The listener not shown was for writing the variable values. Once I simply added this, to the first listener:

try {
                    bufferFileWriter.close();
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }

the variable values were written to my file.

Answer 2

In order to get the button that is being pressed, you need to get the action command from the event. You can do this like:

new ActionListener() {
    public void actionPerformed(ActionEvent e)
    {
        if (e.getActionCommand().equals("Save")) {
            // perform save code
        }
    }
}

"Save" is whatever the name of the JButton is.