Action Listener

Question

以下代码是项目的操作侦听器。基本上，我有4个单选按钮，当我点击一个按钮时，我希望它在屏幕上更改一个变量。当我运行代码时，它只是将所有值加在一起。有没有其他方法可以做到这一点？

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

的问题是，对于每个if()语句，如如果（Button32.isSelected（））;，结尾处有一个;符号。这不应该在那里。下面是更正后的代码...

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); 
     } 
    } 
} 

作为一种选择，你为什么不得到从ActionEvent被点击的按钮，然后使用该按钮在你的if-else分支...

“

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); 
      } 
     } 
    } 
}