Java 对象和方法

Question

我试图了解对象如何在 Java 上与自动变速箱车辆程序一起工作。我有一种方法可以提高汽车的速度speedIncrease，另一种方法可以获取当前对象的速度currentSpeed。在我的测试用例中，我在名为 renault 的 TransmissionBox 对象上创建了初始速度为 25 的对象。 speedUp 方法将速度增加 2，因此新速度应为 27。似乎该对象在第一次调用后丢失了所有修改。这怎么可能？

测试:设置

  @Before
  public void setUp(){
    private TransmissionBox renault;
    renault = new TransmissionBox(25,10,20,30,40,50);
  }

测试:速度 = 27

  @Test
  public void speedIncrease(){
   assertEquals(27,renault.speedUp().currentSpeed());
  }

测试:速度 = 25

  @Test
  public void speedIncrease(){
   renault.speedUp();
   assertEquals(25,renault.currentSpeed());
  }


**TransmissionBox class**

public class TransmissionBox {
private int speed;
private int gear;
private int threesholdOne;
private int threesholdTwo;
private int threesholdThree;
private int threesholdFour;
private int threesholdFive;



  public TransmissionBox(int iniSpeed, int iniThresholdOne, int iniThresholdTwo, int iniThresholdThree, int iniThresholdFour, int iniThresholdFive){
      this.speed = iniSpeed;
      this.threesholdOne = iniThresholdOne;
      this.threesholdTwo = iniThresholdTwo;
      this.threesholdThree = iniThresholdThree;
      this.threesholdFour = iniThresholdFour;
      this.threesholdFive = iniThresholdFive;

      if(speed == 0 && speed < threesholdOne){
        this.gear = 1;
      }

    else if(speed > threesholdOne && speed < threesholdTwo){
      this.gear = 2;
    }

    else if(speed > threesholdTwo && speed < threesholdThree){
        this.gear = 3;
    }

    else if(speed > threesholdThree && speed < threesholdFour){
        this.gear = 4;
    }

    else{
        this.gear = 5;
    }

  }


  public TransmissionBox speedUp(){
    TransmissionBox fasterCar = new TransmissionBox(speed+2, threesholdOne, threesholdTwo, threesholdThree, threesholdFour, threesholdFive);
    return fasterCar;
  }

  public TransmissionBox speedDown(){
    TransmissionBox slowerCar = new TransmissionBox(speed-2, threesholdOne, threesholdTwo, threesholdThree, threesholdFour, threesholdFive);
    return slowerCar;
  }

  public int currentSpeed(){
    return this.speed;
  }

  public int currentGear(){
    return this.gear;
  }


  public String toString(){
    return "speed: " + this.speed + "\n gear: " + this.gear;
  }
}

Answer 1

您在错误的测试中调用了 speedUp()