1

对于我的课程，我需要使用我的 ActionListener。我无法将我的 ActionListener 添加到我的按钮。我必须像 this.buttons 一样使用“this”这个词来添加我的 ActionListener，但我在这样做时遇到了麻烦。稍后我将介绍我的 actionPerformed 方法，但我的主要问题是我的 ActionListener。

public class TextButtonsHW extends JFrame implements ActionListener {
private JButton[] buttons;  //Do not change
private JTextArea textArea; //Do not change
//Assign values for these constants in the constructor
private final int ENTER;    //Index of Enter button in buttons
private final int SPACE;    //Index of Space button in buttons
private final int CLEAR;    //Index of Clear button in buttons

/**
 * Set up this frame and its contents.
 * @param title Title to appear in JFrame title bar
 */
public TextButtonsHW(String title) {

    super(title); //call parent JFrame constructor to set the title

    buttons = new JButton[] { new JButton("A"), new JButton("B"), new JButton("C"),
                  new JButton("1"), new JButton("2"), new JButton("3"),
                  new JButton("X"), new JButton("Y"), new JButton("Z"),
                  new JButton("Enter"), new JButton("Space"), new JButton("Clear")};

    ENTER = buttons.length-3;
    SPACE = buttons.length-2;
    CLEAR = buttons.length-1;

    textArea = new JTextArea(15, 5);
    textArea.setEditable(false);

    this.buttons[0].addActionListener(I dont know what to put right here);

    //TODO: instantiate all JButtons, add them to the buttons array,
    //  and register "this" as the ActionListener for each button.
    //DONE
    //TODO: assign values to ENTER, SPACE, and CLEAR constants to
    //  indicate the indexes of those buttons in the buttons array
    //DONE
    //TODO: create the JTextArea textArea
    //TODO: set its "editable" property to false
    //DONE
    //Create a TextButtonsHWPanel to display the buttons and textArea

    TextButtonsHWPanel mainPanel = new TextButtonsHWPanel(buttons, textArea);
    this.getContentPane().add(mainPanel);
    this.pack();
}


public void actionPerformed(ActionEvent e) {


    //TODO: update the text of textArea according to which
    //  button generated the ActionEvent.

}


public static void main(String[] args) {
    final TextButtonsHW f = new TextButtonsHW("Text Buttons");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setLocationRelativeTo(null); //centers frame on screen
    f.setVisible(true);
}

}

4

3 回答 3

5 
buttons[0].addActionListener(this);
于 2013-04-22T04:09:50.500 回答
2

由于您有 12 个按钮，您还可以使用 for 循环将 ActionListener 添加到所有按钮，即

for(int i=0; i<12; i++)
{
    buttons[i].addActionListener(this);
}

而不是长代码，即

buttons[0].addActionListener(this);
buttons[1].addActionListener(this);
........................
于 2013-04-22T04:47:04.690 回答
0

虽然buttons[0].addActionListener(this);效果很好，但从设计的角度来看，我建议使用单独的类（可能是内部类）来实现ActionListner并将其对象引用传递给方法。

面向对象编程的重点是将不同的职责委托给不同的对象（类），因此代码变得更加可维护和可重用。

于 2013-04-22T06:02:30.887 回答