Question

public Quiz(){
    frame = new JFrame();
    frame.setSize(500, 500);
    frame.setLocationRelativeTo(null);
    frame.setTitle("x");
    frame.getContentPane().setBackground(Color.GRAY);
    frame.setLayout(new FlowLayout());

    label = new JLabel("What is...?");
    frame.add(label);

    choiceA = new JRadioButton("A", true); 

            //this if statement happens even if I click on one of the other radio buttons and if I leave this one set to false then none of the events happen

    choiceB = new JRadioButton("B");
    choiceC = new JRadioButton("C");
    choiceD = new JRadioButton("D");
    frame.add(choiceA);
    frame.add(choiceB);
    frame.add(choiceC);
    frame.add(choiceD);

    group = new ButtonGroup();
    group.add(choiceA);
    group.add(choiceB);
    group.add(choiceC);
    group.add(choiceD);


    checkButton = new JButton("Check");
    frame.add(checkButton);

    Handler handler = new Handler();
    checkButton.addActionListener(handler);
    choiceA.addActionListener(handler);
    choiceB.addActionListener(handler);
    choiceC.addActionListener(handler);
    choiceD.addActionListener(handler);


}


public static void main (String args[]){
    Quiz quiz = new Quiz();
    quiz.frame.setResizable(false);
    quiz.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    quiz.frame.setVisible(true);
}

private class Handler implements ActionListener{
    public void actionPerformed(ActionEvent event){
        checkButtonActionPerformed(event);

        }

    public void checkButtonActionPerformed(ActionEvent event){
        Quiz quiz = new Quiz();
        if(quiz.choiceA.isSelected()){
            System.out.println("wow");
        }
        else if(quiz.choiceB.isSelected()){
            System.out.println("not wow");
        }
        else if(quiz.choiceD.isSelected()){
            System.out.println("why doesn't this work?");
        }
    }
}
}

我只是希望每个字符串在被选中之后打印出来并按下JButton，但是除非我在运行代码之前将其中一个设置为true，否则它们都不会工作，如果我这样做它就没有＆＃39 ;无论我检查了哪个单选按钮，当我点击JButton来执行我最初设置为true的if语句时

Answer 1

问题是您在Quiz方法中创建actionPerformed的新实例...

public void checkButtonActionPerformed(ActionEvent event){
    Quiz quiz = new Quiz();

这意味着您所比较的内容并不是屏幕上的实际内容。

如果Handler是内部类，则可以直接引用变量...

if(choiceA.isSelected()){...}

否则你应该将Quiz的引用传递给Handler以供它使用，但我会建议你这样做会变得更复杂，实际上需要某种可能的getter方法告诉我们选择了什么

我的JRadioButtons没有与我的JButton进行交互

1 个答案: