防止超出指定范围的值

Question

private int currentSpeed;
private static final int MAXIMUM_SPEED = 100;
private int heading;

int speedUp(int increaseBy) {

    currentSpeed += increaseBy;

    return currentSpeed;
}

int slowDown(int decreaseBy) {

    currentSpeed -= decreaseBy;

    return currentSpeed;
}

如何防止值currentSpeed超出speedUp方法中的MAXIMUM_VALUE变量，以及在slowDown方法中不使用if语句时降低0以下。我相信使用Math.min＆amp; Math.max可行，但我不确定如何实施。

Answer 1

使用Math.max和Math.min，如下所示：

int speedUp(int increaseBy) {
    currentSpeed = Math.min(currentSpeed + increaseBy,MAXIMUM_SPEED);
    return currentSpeed;
}

int slowDown(int decreaseBy) {
    currentSpeed = Math.max(currentSpeed - decreaseBy,0);
    return currentSpeed;
}

Answer 2

你应该能够使用ternary operator

int speedUp(int increaseBy) {
    currentSpeed = currentSpeed + increaseBy < MAXIMUM_SPEED ? currentSpeed += increaseBy : MAXIMUM_SPEED;
    return currentSpeed;
}

int slowDown(int decreaseBy) {
    currentSpeed = currentSpeed - decreaseBy > 0 ? currentSpeed -= decreaseBy : 0;
    return currentSpeed;
}