需要帮助找出错误

Question

我有以下代码，其中包含运行时间错误。该代码旨在打印出：

车辆mode:flightFuel:propane最大Altitude:10000

车辆mode:traversalFuel:coalHorsepower:5000

我自己找不到它（因为我对编码还很陌生），如果可能的话希望得到一些帮助。

谢谢。

class Main {

public static void main(String[] args) {

    HotAirBalloon airbag = new HotAirBalloon(10000);
    Locomotive loco = new Locomotive(5000);

    System.out.println(airbag.toString());
    System.out.println(loco.toString());
}
}

class Vehicle {

String mode, fuel;

public String toString() {
    return "Vehicle Mode:" + mode + " Fuel:" + fuel;
}
}

class HotAirBalloon extends Vehicle {

int maxAltitude;

HotAirBalloon(int _alt) {
    mode = "flight";
    fuel = "propane";
    maxAltitude = _alt;
}
public String toString() {
    return toString() + " Max Altitude:" + maxAltitude;
}

}

class Locomotive extends Vehicle {

int horsePower;
Locomotive(int _hp) {
    mode = "traversal";
    fuel = "coal";
    horsePower = _hp;

}
public String toString() {
    return toString() + " Horsepower:" + horsePower;
}

}

Answer 1

因为您正在尝试调用当前方法的超级类版本，您需要添加 super.toString()

//old
return toString() + " Horsepower:" + horsePower;
//new
return super.toString() + " Horsepower:" + horsePower;

您还需要对其他子类执行此操作

当您调用自己的方法时，它称为递归，其中方法会不断调用自己，直到达到特定条件。

Answer 2

此代码可以正常工作。问题是您多次调用 toString() 导致 Stack 溢出。另外，您必须在父 class 车辆中声明一个字符串，并在子 classes 中使用飞行模式等更新它。运行下面的代码：

class Main {

public static void main(String[] args) {

    HotAirBalloon airbag = new HotAirBalloon(10000);
    Locomotive loco = new Locomotive(5000);

System.out.println(airbag.toString());
System.out.println(loco.toString());
}
}

class Vehicle {
String mode, fuel;
String s;
}

class HotAirBalloon extends Vehicle {

int maxAltitude;

HotAirBalloon(int _alt) {
    mode = "flight";
    fuel = "propane";
    maxAltitude = _alt;
    s= "Vehicle Mode:" + mode + " Fuel:" + fuel;
}
public String toString() {
    return s + " Max Altitude:" + maxAltitude;
}}

class Locomotive extends Vehicle {

int horsePower;
Locomotive(int _hp) {
mode = "traversal";
fuel = "coal";
horsePower = _hp;
s= "Vehicle Mode:" + mode + " Fuel:" + fuel;

}
public String toString() {
return s+ " Horsepower:" + horsePower;
}
}

需要帮助找出错误

Need help finding the error

java

error-handling

runtime-error