java - 如何停止计时器

Question

我有执行以下操作的方法

public void actionPerformed(ActionEvent e) {

    Timer timer = new Timer();
    Object source = e.getSource();

    String stringfromDate = tffromDate.getText();
    String stringtoDate = tftoDate.getText();

    if (source == button) {
        // auto refresh begins
        int delay = 0; // 0 seconds startup delay
        int period = 7000; // x seconds between refreshes
        timer.scheduleAtFixedRate(new TimerTask()
        {
            @Override
            // i still have to truly understand what overide does however
            // netbeans prompted me to put this
            public void run() {

                try {
                    getdata(stringfromDate, stringtoDate);// run get data
                                                            // method
                } catch (IOException | BadLocationException ex) {
                    Logger.getLogger(JavaApplication63.class.getName())
                            .log(Level.SEVERE, null, ex);
                }
            }
        }, delay, period);
    }

    if (source == button1) {
        timer.cancel();

        textarea.setText("");
    }
}

我的 GUI 上有 2 个按钮，一个称为获取信息(按钮)，另一个称为清除信息(按钮 1)。 我似乎无法获得清晰的信息(按钮1)来停止计时器并清除文本区域，以便可以执行新的搜索。我似乎无法让这停止帮助赞赏。

Answer 1

考虑对您的代码进行这些更改。主要是代码以不同的方式执行这些操作:

• 将计时器的声明拉到类中，以便稍后可以取消之前启动的同一计时器。

• 仅在按下开始按钮时创建一个新计时器。

  //Pulled up for access to make canceable .
  protected Timer timer;
  
  public void actionPerformed(ActionEvent e) {
  
    Object source = e.getSource();
  
    String stringfromDate = tffromDate.getText();
    String stringtoDate = tftoDate.getText();
  
    if (source == button) {
      //Stop existing one before creating new.
      if(timer != null) {
          timer.cancel();
      }
      //Now make new
      timer = new Timer();
  
      // auto refresh begins
      int delay = 0; // 0 seconds startup delay
      int period = 7000; // x seconds between refreshes
      timer.scheduleAtFixedRate(new TimerTask() {
          @Override 
          public void run() {
  
              try {
                  getdata(stringfromDate, stringtoDate);// run get data
                                                          // method
              } catch (IOException | BadLocationException ex) {
                  Logger.getLogger(JavaApplication63.class.getName()).log(Level.SEVERE, null, ex);
  
              }
  
          }
      }, delay, period);
    }
    if (source == button1) {          
      //NULLCHECK
      if(timer != null) {
          timer.cancel();
      }
      textarea.setText("");
    }
  }