用初始化的对象填充 ArrayList

Question

我在 Class 中有 ArrayList 卡片组 Deck.I 想用 Card 对象填充 ArrayList。

我还想填充Card对象的属性。

我添加了一个 for 循环来查看结果，ArrayList 有 5 个名称为 NULL 且值为 0 的对象。

(FillDeck已在主函数中调用)

import java.util.ArrayList;


public class Deck {

    private ArrayList<Card> deck=new ArrayList();


      public Deck(){

    }


      public Deck(ArrayList<Card> deck ){

        this.deck = deck;

    }

          //hearts,spades,diamonds,clubs  
        Card card1 = new Card("A hearts",11,true);
        Card card2 = new Card("2 hearts",2,true);
        Card card3 = new Card("3 hearts",3,true);
        Card card4 = new Card("4 hearts",4,true);    
        Card card5 = new Card("5 hearts",5,true);




    public void filldeck(){





        deck.add(card1);       
        deck.add(card2);       
        deck.add(card3);      
        deck.add(card4);     
        deck.add(card5);       


          for (int i=0; i<deck.size(); i++){

              System.out.println(deck.get(i).getName());
              System.out.println(deck.get(i).getValue());


          }

    }


}




public class Card {


    private String name;
    private int value;
    private boolean samecard = true ;

    public Card(){

    }

    public Card(String name,int value,boolean samecard){

        name = this.name;
        value = this.value;
        samecard = this.samecard;
    }

    public String getName(){

        return name;
    }

    public int getValue(){

        return value;
    }

    public boolean getSamecard(){

        return samecard;
    }
}

Answer 1

因为您看到的是字段的默认值。要解决这个问题，您必须实际分配值，例如

public Card(String name,int value,boolean samecard){
    this.name = name;
    this.value = value;
    this.samecard = samecard;
}

Answer 2

您的Card(String name, int value, boolean samecard)实现错误，您不能将实例变量分配给构造函数参数。

要明确这是错误的：name = this.name

这是正确的：this.name = name

这是一个正确的实现：

    public Card(String name,int value,boolean samecard){
        this.name = name;
        this.value = value;
        this.samecard = samecard;
    }

Answer 3

您在 Card class 中搞砸了构造函数，将构造函数变量赋值更改为：

this.name = name;
this.value = value;
this.samecard = samecard;

Answer 4

您的承包商有问题。它看起来像这样：

public Card(String name,int value,boolean samecard){
    name = this.name;
    value = this.value;
    samecard = this.samecard;
}

应该是这样的：

public Card(String name,int value,boolean samecard){
    this.name = name;
    this.value = value;
    this.samecard = samecard;
}

Answer 5

你是qualifying作业的右边，在这种情况下是不正确的：

public Card(String name,int value,boolean samecard){

    name = this.name;
    value = this.value;
    samecard = this.samecard;
}

一定是

public Card(String name,int value,boolean samecard){

    this.name = name;
    this.value = value;
    this.samecard = samecard;
}

用初始化的对象填充 ArrayList

Filling ArrayList with initialized Objects

java

null

arraylist

object

fill