非活动按钮按下 (Java Swing)答案

【问题标题】：Inactive Button Presses (Java Swing)非活动按钮按下 (Java Swing)
【发布时间】：2014-11-28 23:42:48
【问题描述】：

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
            }
        }
}

你好。在这个程序中，用户将按下JButton one。在 3 秒内连续按下one 并将字符串“1”附加到tempNum 的用户。当用户在 3 秒后按下另一个 one 时，tempNum 的值将仅为“1”。我的问题是：最初，当用户按下一个全新的“1”时，你如何检测用户是否处于非活动状态 3 秒？

例如：
输入：用户输入：1
你如何检测用户是否在 3 秒后没有按下任何东西？

【问题讨论】：

标签： java swing jbutton actionlistener

【解决方案1】：

声明长按 = null;它的初始值为 null，表示用户尚未按下按钮。

/**
 * 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
    }
}

【讨论】：