java - 如何在 Java 中在一段时间后结束一个方法？

Question

我想强制一个方法在一定时间后结束，即使它尚未完成其任务。我该如何去做呢？

编辑(添加说明和代码):我正在使用 Android Studio 为 FTC(First Tech Challenge)机器人竞赛编写一个机器人。为了控制机器人，我使用 FTC SDK(请参阅 https://github.com/ftctechnh/ftc_app )。

该方法对于行驶特定距离然后停止来说效果很好，但是在通过将所有电机的功率设置为零而停止后，它似乎挂起并且没有调用后续方法。目前，它只应该让电机在退出前停止一秒钟，但在第一次调用将电机功率设置为零 (setPower) 的方法时，它似乎仍然卡住。因此，我希望能够在 setPower 运行一定时间后终止它，以便我的方法可以退出并调用后续方法。

这是我的方法:

public void moveLine(DcMotor m1, DcMotor m2, DcMotor m3, DcMotor m4, double distance /* distance to move in meters */, double motorPower /* power to set the motors */) {

    final double SPROCKET_CIRCUMFRENCE = Math.PI * 0.0652; //calculates the circumference of the sprocket
    final int ENCODER_CPR_NR60 = 1680; //encoder counts for NeveRest 60
    //final static int ENCODER_CPR_NR40 = 1120; //encoder counts for NeveRest 40

    double amountOfRotationsCalc = distance / SPROCKET_CIRCUMFRENCE; //calculates the amount of rotations to move to reach the target distance

    double amountOfEncUnitsCalc = ENCODER_CPR_NR60 * amountOfRotationsCalc; //calculates the amount of encoder units to move

    //this gets the sum of the encoder positions of the drive motors
    int currentEncPosSum = m1.getCurrentPosition() + m2.getCurrentPosition() + m3.getCurrentPosition() + m4.getCurrentPosition();

    //this gets the average encoder position
    int currentEncPosAvg = currentEncPosSum / 4;

    //if the robot is supposed to be moving forward (positive distance), the motors will be set to positive values
    if (distance > 0) {

        //it may make sense to make this a while loop. Will this fix the issue?
        if (currentEncPosAvg < amountOfEncUnitsCalc) {
            m1.setPower(motorPower);
            m2.setPower(motorPower);
            m3.setPower(motorPower);
            m4.setPower(motorPower);
        } else {
            //these stop the robot. Without them, it continues to move.
            long start = System.currentTimeMillis();
            long end = start + 1000;
            while (System.currentTimeMillis() < end) {
                m1.setPower(0);
                m2.setPower(0);
                m3.setPower(0);
                m4.setPower(0);
            }
            return; //this is supposed to exit this method
        }

    } else {

        //this is essentially the opposite of the code for going forwards
        if (currentEncPosAvg > amountOfEncUnitsCalc) {
            m1.setPower(-motorPower);
            m2.setPower(-motorPower);
            m3.setPower(-motorPower);
            m4.setPower(-motorPower);
        } else {
            //these stop the robot. Without them, it continues to move.
            long start = System.currentTimeMillis();
            long end = start + 1000;
            while (System.currentTimeMillis() < end) {
                m1.setPower(0);
                m2.setPower(0);
                m3.setPower(0);
                m4.setPower(0);
            }
            return;
        }

    }

}

Answer 1

long beginning = System.currentTimeMillis();
long end=beginning + yourTimeInMilliseconds;
while (end > System.currentTimeMillis()){
    //your code here
}

我相信这就是你的意思。

一些说明(如果您需要的话):begin 是当前时间(以毫秒为单位)。end 显然是结束的时候。 (开始时间加上延迟)虽然时间仍然小于设定的结束时间，但代码继续执行。