java - 尝试从另一个子类继承时出错？

Question

public class Vehicle {

  private double speed;
  private int wheels;

  public Vehicle() {

  }

  public Vehicle(double speed, int wheels) {
    this.speed = speed;
    this.wheels = wheels;
  }

}


public class Motorcycle extends Vehicle {

  private double engineSize;

  public Motorcycle(double speed, double engine) {
    super(speed, 2);
    this.engineSize = engine;
  }

}


public class Moped extends Motorcycle {


}

既然 Mope 扩展了 Motorcycle，为什么它告诉我 Moped 需要创建一个构造函数？我希望轻便摩托车无需任何构造函数即可工作。

Answer 1

因为 Motorcycle 没有默认构造函数，因此您无法在 Moped 中使用它 - 但您可以添加一个空构造函数对于 Moped - 就像，

public class Moped extends Motorcycle {
    public Moped() {
        super(70, 50); //<-- or whatever values you want 
    }
}