共享变量判断是否有存在的任务

  // 共享变量
    private static volatile int sharedNumber = 0;
    // 锁对象
    private static final Object lock = new Object();
    // 检查方法
    public static boolean checkAndExecute() {
        synchronized (lock) {
            if (sharedNumber == 0) {
                return false;
            } else if (sharedNumber == 1) {
                return true;
            } else {
                return false;
            }
        }
    }
// 设置变量值
    public static void setNumber(int value) {
        synchronized (lock) {
            sharedNumber = value;
            System.out.println("Shared number set to " + value);
        }
    }
  // 执行放
public void execute(){
// 设置执行
  setNumber(1);
    .......
  // 结束释放
  setNumber(0);
}