java - 将方法返回值存储在 ArrayList 中

Question

我正在编写一个程序来创建游戏板，并使用父类(super class)和子类来生成游戏板。本质上，我想使用一个 arrayList 来存储从 Cell 子类的方法返回的值。但我不知道该怎么做。我在 BoardGame 类中编写的内容给了我一个错误，我想不出其他方法来做到这一点。

import java.util.ArrayList;


public class BoardGame {



    private Die theDie;



    BoardGame(){





    }

    void buildBoard(){

        ArrayList<Player> player;




        Cell c = new Cell();

        ArrayList<Cell>cells = new ArrayList<Cell>();

        cells.add(c.landOn());

    }

    void runSimulation(){

    }


     int takeTurn(String n){

         //since we don't know what we are returning yet
         return 0;


    }

     String toString(String n){


         //Since we aren't returning anything yet
         return "Nothing";


     }
}






public class Cell {

    static int landOn(){


        //Since we do not know what we are returning
        return 0;
    }

    public String toString(){



        //Since we do not know what we are returning
        return "Blank";
    }

}




public class Star extends Cell {

    int landOn(){


        //since we do not know what we are returning 
        return 5;
    }

    public String toString(){


        //since we do not know what we are returning
        return "Star: +5";
    }

}



public class Lightning extends Cell {

    int landOn(){


        //since we do not know what we are returning 
        return -5;
    }

    public String toString(){


        //since we do not know what we are returning
        return "Lightning: -5";
    }

}



public class X extends Cell {

    int landOn(){


        //since we do not know what we are returning 
        return -10;
    }

    public String toString(){


        //since we do not know what we are returning
        return "X: -10";
    }

}



public class Smiley extends Cell {

    int landOn(){


        //since we do not know what we are returning 
        return 10;
    }

    public String toString(){


        //since we do not know what we are returning
        return "Smiley: +10";
    }

}

Answer 1

您的ArrayList被声明为Cell您的方法的返回类型是int。您的 ArrayList 不能存储除 Cell 类型的实例之外的任何内容

要存储方法的所有返回类型，您需要一个Integer类型的ArrayList

使用 int 也不起作用，因为 int 是一个原语。

解决方案:

ArrayList<Integer> cells = new ArrayList<>();