在java中使用继承时出现错误消息

Question

我对java中的继承不熟悉，我有以下问题。我的基类是Plane，它的子类是PlaneComponent，PlaneComponent的子类是PasengerCom的。我的程序由11个类组成，当我忽略PasengerCom的类时，一切都是正确的。但是当我运行整个程序时，我收到了这个消息：at Plane。

飞机：

import java.util.*;

public class Plane
{
int cap;
int pl;

public Plane()
{
    String desc = "Plane Description";
    String title = "Boeing 747";
    Random rand = new Random();
    cap = rand.nextInt(100) + 51;       //initialize cap with 50<value<100
    **PassengerCompartment a8 = new PassengerCompartment();**
    pl = cap / a8.cap2;                 // pl = sum of Passenger Compartments
    if (cap % a8.cap2 != 0)
    {
        pl = pl - (cap % a8.cap2) + 1;
    }
}
public boolean ready_check()
{
    CargoBay a6 = new CargoBay();
    a6.ready_check();
    for (int i = 0 ; i < 3 ; i++)
    {
        EquipmentCompartment a7 = new EquipmentCompartment();
        a7.ready_check();
    }
    for(int i = 0; i < pl; i++)
    {
        PassengerCompartment a8 = new PassengerCompartment();
        a8.ready_check();
    }
    System.out.println("Plane OK!");
    return true;
}
public void process(String e)
{
    if(e == "SecurityEmployee")
    {
        SecurityEmployee a14 = new SecurityEmployee();
        a14.workOn();
    }
    if(e == "MaintenanceEmployee")
    {
        MaintenanceEmployee a15 = new MaintenanceEmployee();
        a15.workOn();
    }
    if(e == "CleaningEmployee")
    {
        CleaningEmployee a16 = new CleaningEmployee();
        a16.workOn();
    }
}

public void values()
{
    System.out.println("Would you like more info about the plane's capacity? type Y or N");
    Scanner input = new Scanner(System.in);
    String inp = input.nextLine();
    while (!(inp.equals("Y")) && !(inp.equals("N")))
    {
        System.out.println("Wrong input, please type again");
        inp = input.nextLine();
    }
    if ( inp.equals("Y"))
    {
        PassengerCompartment a8 = new PassengerCompartment();
        System.out.println("Plane's capacity: " + cap);
        System.out.println("PassComp's capacity: " + a8.cap2);
        System.out.println("Number ofPassenger Compartments " + pl);
    }
}

}

飞机组件：

**public class PlaneComponent extends Plane**
{
public boolean ready_check()
{
    return true;
}

public void process(String desc)
{
    Employee.workOn(desc);
}
}

乘客车厢:

import java.util.*;

public class PassengerCompartment extends PlaneComponent
{
Random rand = new Random();
boolean inner = rand.nextBoolean();
int cap2;
String desc;

public PassengerCompartment()
**{**
    desc = "Passenger Compartment";
    cap2 = rand.nextInt(50) + 21;       //initialize cap with 20<value<50
}
public boolean ready_check()
{
    System.out.println(desc);
    if (super.ready_check() == true)
    {
        System.out.println("Passenger Compartment OK!");
        if (inner == true)
        {
            desc = "Inner Compartment";
            System.out.println(desc);
            if (super.ready_check() == true)
            {
                System.out.println("Inner Compartment OK!");
            }
        }
    }
    return true;
}
public void process(String desc)
{
    super.process(desc);
}
}




Answer 1

你的问题在于你的继承结构。

在Plane的构造函数中，创建一个PassengerCompany实例<乘客舱扩展了飞机舱PlaneCompartment扩展“Plane”。所以，你在一个圆圈里。

我认为飞机舱扩展飞机没有意义。你所拥有的是一种“拥有-拥有”的关系。因此，< code>Plane有一个< code>PlaneCompartment，但两者都不互相扩展。

Answer 2

匿名用户

您有一种循环继承类型的情况（ 可能 会创建StackOverflow异常）：

您实例化< code > passenger compartment A8 = new passenger compartment()；在< code>Plane的构造函数中。

PassengerCompany扩展了PlaneComponent，因此隐式调用了PlaneComponent的构造函数（super（）），该构造函数继承自Plane。在＜code＞Plane＜/code＞的构造函数中，您有提到的＜code＞PassengerCompartment＜/code’的实例化等等…所以我强烈建议不要在所述类的构造函数中实例化继承自类的类。

我建议在这里阅读我的关于这个主题的问答。