Question

帮助尝试增加和减少按钮，增加和减少面板上的数字只是不起作用，我试图获得actionPerformed并且动作监听器不工作可能有人给我指导`

public class IncrDecPanel extends JPanel  
{




private int INITIAL_NUMBER = 50;
private JButton Incr, Dec;
private JLabel label;
private JPanel ButtonPanel; 
private int number;

public IncrDecPanel()
{ 


    number = INITIAL_NUMBER;

    label = new JLabel(String.valueOf(number));

    Incr = new JButton("Incr");
    Dec = new JButton("Dec");


     JButton IncrButton = new JButton("Increment");
     IncrButton.addActionListener (new IncrListener());


    JButton DecButton = new JButton("Decrement");
     DecButton.addActionListener(new DecListener());



      ButtonPanel = new JPanel();
      ButtonPanel.setPreferredSize(new Dimension(200, 40));
      ButtonPanel.setBackground(Color.red);
      ButtonPanel.add(Incr);
      ButtonPanel.add(Dec);

      12
      setPreferredSize(new Dimension(200, 80));
      setBackground(Color.black);
      add(label);
      add(ButtonPanel);
}


 private class IncrListener implements ActionListener
   {

      public void actionPerformed (ActionEvent event)
      {
         label.setText (Integer.toString (++number));
      }
   }
         private class DecListener implements ActionListener
         {

            public void actionPerformed (ActionEvent event)
            {
               label.setText (Integer.toString (--number));
            }

      }
 }`

Answer 1

您将ActionListeners添加到错误的按钮。您已创建按钮Incr和Dec，然后将您的听众添加到IncrButton和DecButton，然后再添加Incr和Dec你的JPanel。只需在创建后将听众分配到第一个按钮，例如：

    Incr = new JButton("Incr");
    Dec = new JButton("Dec");

    Incr.addActionListener(new IncrListener());
    Dec.addActionListener(new DecListener());

希望这会有所帮助。：）

增加和减少gui不增加不确定我是否出错

1 个答案: