java - Action 监听器

Question

以下代码是项目的操作监听器。基本上，我有 4 个单选按钮，当我单击其中一个时，我希望它更改屏幕上的变量。当我运行代码时，它只是将所有值加在一起。还有其他方法可以做到这一点吗？

class Calc implements ActionListener
    {
     public void actionPerformed(ActionEvent event)
     {
       double base = 0.00;
       double options;
       double total;

      if (Button25.isSelected());
      {
      base = base + 999.99;
      String base2 = Double.toString(base);
      lblBaseAns.setText(base2);
      }

      if (Button32.isSelected());
      {
        base = base + 1049.99;
        String base2 = Double.toString(base);
        lblBaseAns.setText(base2);
      }

      if (Button35.isSelected());
      {
        base = base + 1099.99;
        String base2 = Double.toString(base);
        lblBaseAns.setText(base2);
      }

      if (Button42.isSelected());
      {
        base = base + 1155.99;
        String base2 = Double.toString(base);
        lblBaseAns.setText(base2);
      }


     }
    }

Answer 1

问题是，对于每个 if() 语句，例如 if (Button32.isSelected());，您都有一个 ; 符号位于末尾。这个不应该在那里。这是更正后的代码...

class Calc implements ActionListener {
    public void actionPerformed(ActionEvent event){
        double base = 0.00;
        double options;
        double total;

        if (Button25.isSelected()){ // changed
            base = base + 999.99;
            String base2 = Double.toString(base);
            lblBaseAns.setText(base2);
        }
        else if (Button32.isSelected()){ // changed
            base = base + 1049.99;
            String base2 = Double.toString(base);
            lblBaseAns.setText(base2);
        }
        else if (Button35.isSelected()){ // changed
            base = base + 1099.99;
            String base2 = Double.toString(base);
            lblBaseAns.setText(base2);
        }
        else if (Button42.isSelected()){ // changed
            base = base + 1155.99;
            String base2 = Double.toString(base);
            lblBaseAns.setText(base2);
        }
    }
}

作为替代方案，为什么不获取从 ActionEvent 单击的按钮，然后在 if-else 分支中使用该按钮...

class Calc implements ActionListener {
    public void actionPerformed(ActionEvent event){
        double base = 0.00;
        double options;
        double total;

        Object clickedObject = event.getSource();
        if (clickedObject instanceof JRadioButton){
            JRadioButton clickedButton = (JRadioButton)clickedObject;

            if (clickedButton == Button25){
                base = base + 999.99;
                String base2 = Double.toString(base);
                lblBaseAns.setText(base2);
            }
            else if (clickedButton == Button32){
                base = base + 1049.99;
                String base2 = Double.toString(base);
                lblBaseAns.setText(base2);
            }
            else if (clickedButton == Button35){
                base = base + 1099.99;
                String base2 = Double.toString(base);
                lblBaseAns.setText(base2);
            }
            else if (clickedButton == Button42){
                base = base + 1155.99;
                String base2 = Double.toString(base);
                lblBaseAns.setText(base2);
            }
        }
    }
}