e979. creating a jtextfield component.txt

这里面包含了一百多个JAVA源文件

When the user hits RETURN, the text field fires an action event. 
    // Create a text field with some initial text
    JTextField textfield = new JTextField("Initial Text");
    
    // Create a text field with some initial text and a default number of columns.
    // The number of columns controls the preferred width of the component;
    // each column is rougly the size of an M in the current font.
    int cols = 30;
    textfield = new JTextField("Initial Text", cols);
    
    // Listen for action events, which are fired when the user hits RETURN
    textfield.addActionListener(new MyActionListener());
    
    class MyActionListener implements ActionListener {
        public void actionPerformed(ActionEvent evt) {
            JTextField textfield = (JTextField)evt.getSource();
            process(textfield.getText());
        }
    }