the getSource() and getActionCommand()

action, event-handling, java, swing, user-interface

Solution

Assuming you are talking about the `ActionEvent` class, then there is a big difference between the two methods.

`getActionCommand()` gives you a String representing the action command. The value is component specific; for a `JButton` you have the option to set the value with `setActionCommand(String command)` but for a `JTextField` if you don't set this, it will automatically give you the value of the text field. According to the javadoc this is for compatability with `java.awt.TextField`.

`getSource()` is specified by the `EventObject` class that `ActionEvent` is a child of (via `java.awt.AWTEvent`). This gives you a reference to the object that the event came from.

Edit:

Here is a example. There are two fields, one has an action command explicitly set, the other doesn't. Type some text into each then press enter.

public class Events implements ActionListener {

  private static JFrame frame; 

  public static void main(String[] args) {

    frame = new JFrame("JTextField events");
    frame.getContentPane().setLayout(new FlowLayout());

    JTextField field1 = new JTextField(10);
    field1.addActionListener(new Events());
    frame.getContentPane().add(new JLabel("Field with no action command set"));
    frame.getContentPane().add(field1);

    JTextField field2 = new JTextField(10);
    field2.addActionListener(new Events());
    field2.setActionCommand("my action command");
    frame.getContentPane().add(new JLabel("Field with an action command set"));
    frame.getContentPane().add(field2);


    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(220, 150);
    frame.setResizable(false);
    frame.setVisible(true);
  }

  @Override
  public void actionPerformed(ActionEvent evt) {
    String cmd = evt.getActionCommand();
    JOptionPane.showMessageDialog(frame, "Command: " + cmd);
  }

}

Problem

Original source