非活动按钮按下（Java Swing）

你好。在此程序中，用户将按

JButton one

。在3秒内连续按

one

并将字符串“1”附加到

tempNum

的用户。当用户在3秒钟后按下另一个

one

时，

tempNum

的值仅为“1”。 我的问题是：最初，当用户按下一个全新的“1”时，如何检测用户是否在3秒钟内处于非活动状态

例如：
输入： 用户输入：1

---

如何检测用户在3秒钟后是否没有按任何键？

声明长按=null；它的初始值将为null，这表示用户尚未按下按钮

String tempNum="";
public void actionPerformed(ActionEvent event) 
    {
        JButton src = (JButton) event.getSource();  
        if(src.equals(one))  
        {
            if (pressed + 3000 > System.currentTimeMillis()) // user press > 3 seconds
            {
                tempNum = tempNum + "1";
                //do a command
            }
            else //new 
            {
                pressed = System.currentTimeMillis();
                tempNum="";
                tempNum = tempNum + "1";
                //do a command
            }
        }
}

/**
 * Declare pressed as Long pressed = null; in your code for the following to work as intended.
 */

StringBuilder tempNum = new StringBuilder(); 
String   TO_ADD   = "1"; 
int      presses  =  0 ;
int      SECONDS  =  3 ; 

public void actionPerformed(ActionEvent event) 
{
    JButton src       = (JButton) event.getSource();  
    /**
     * Do call System.currentTimeMillis() once at the beginning and store it's value as later calls System.currentTimeMillis() could return later time.
     */
    long    pressTime = System.currentTimeMillis();

    if(src.equals(one))  
    {
        /**
         * No press was done
         */
        if (null == pressed)
        {
            pressed = pressTime;
        }

        if (pressed + SECONDS*1000 > pressTime) // user press > 3 seconds
        {
            presses++;
            //do a command
        }
        else //new 
        {
            pressed = pressTime;
            presses = 1        ;
            tempNum = new StringBuilder();
            //do a command
        }
        tempNum.append(TO_ADD); //to get string call tempNum.toString(); in your code
    }
}