java - 从 JRadioButton 获取值

Question

当我选择右键并单击 JRadio 框架上的“确定”时，我想更改变量“名称”的值。

例如，当我选择 r1 并点击“确定”时，我希望整个包中包含 name==“Fast”。

package Snake;
public class Radio extends JFrame {
    private int delay = 100;
    private String name;
    JTextField t1;
    JButton b;
    JRadioButton r1, r2;
    JLabel l;

    public void selectSpeed() {

        b = new JButton("Ok");
        r1 = new JRadioButton("Fast");
        r2 = new JRadioButton("Slow");
        l = new JLabel("Speed: ");

        ButtonGroup bg = new ButtonGroup();
        bg.add(r1);
        bg.add(r2);
        add(b);
        add(r1);
        add(r2);
        add(l);

        b.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent arg0) {

                if (r1.isSelected()) {
                    name = "Fast";
                } else {
                    name = "Slow";
                }
                l.setText("Speed: " + name); // name=="Fast" when r1 is selected
            } // name=="Slow" when r2 is selected
        });
        if (name == "Fast") { // and now name is empty...
            delay = 50;

        }
        if (name == "Slow") {
            delay = 500;
        }

        setLayout(new FlowLayout());
        setSize(400, 400);
        setVisible(true);
    }

    public int setSpeed() {
        selectSpeed();
        return delay;

    }

}

Answer 1

如果您想更改按钮单击上的延迟，您需要在ActionListener本身中编写逻辑，因为您编写的用于更改延迟的代码只会运行一次，而且在程序执行开始时也会运行一次，那时，name将为空。

那么当你点击按钮时，它只会执行ActionListener，所以delay不会随时改变。您犯的另一个错误是您以错误的方式比较字符串。欲了解更多信息，请查看 How do I compare Strings in Java?

要动态更改按钮单击时的延迟，您需要在 ActionListener 中更改它。

 b.addActionListener(new ActionListener() {

    public void actionPerformed(ActionEvent arg0) {

        if (r1.isSelected()) {
            name = "Fast";
            delay = 50;
        } else {
            name = "Slow";
            delay = 500;
        }
        l.setText("Speed: " + name); // name=="Fast" when r1 is selected
    } // name=="Slow" when r2 is selected
});