Question

我有以下代码，其中包含运行时错误。该代码打算打印出来：

车辆模式：飞行燃料：丙烷最高海拔高度：10000

车辆模式：遍历燃料：煤马力：5000

我自己找不到（因为我对编码很新）并希望在可能的情况下提供一些帮助。

感谢。

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

因为你试图调用当前方法的超类版本，你需要添加super.toString（）

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

您还需要与其他子类

一起执行此操作

当一个方法调用它自己的被调用的递归时，一个方法一直调用自己直到某个条件。

Answer 2

这段代码会很好。问题是你多次调用toString（）导致Stack溢出。另外，您必须在父类车辆中声明一个String，并在具有飞行模式等的子类中更新它。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;
}
}

需要帮助找到错误

2 个答案: