簡單的方法用一種方法將3種不同類型的對象添加到一個ArrayList中？

Question

這是我完成作業的副本，所以對於挪威的一些評論道歉。

我的問題是：
我有一個項目ArrayList，它包含類Item，Swords，Potions的對象。 （藥水&劍是物品的子類）。我有3種不同的方法將這些對象添加到ArrayList。

我的問題其實很簡單。有沒有一種（簡單的，我是新的和學習仍然）的方式，我沒有3種不同的方法看起來都一樣，所以將所有Item和Item的子類添加到ArrayList。 （addItem，addSword，addPotion），都接近代碼的底部。

我想是這樣的（通過沒有想過，只是寫的東西）

public void addItem(String typeofItem){ 
    item = new typeofItem; 
    items.add(item); 
} 

有很多更多的代碼，但我覺得這是什麼有關。

public class Player 
{ 
    // Fields ------- 
    private String name; 
    private String type; 
    private int health; 
    private ArrayList<Item> items = new ArrayList<>(); 
    private Item item; 
    private Swords sword; 
    private Potions potion; 
    private Checker valid; 
    private int maxCarry; 
    private int gold; 
    private int currentWeight; 
    // ---------------- 

    /** 
    * Klassens konstruktør. Players health vil alltid settes til 100. 
    * 
    * @param name   Player navn 
    * @param type   Player type 
    * @param goldValue Players starting gold 
    * @param setMaxWeight Players max carry weight 
    */ 
    public Player (String name, String type, int goldValue, int setMaxWeight) { 
     valid = new Checker();      // Creates a checker object to do String and integer checks 

     this.name = valid.checkString(name);   // Setter player name, etter å ha sjekka at den ikke er tom 
     this.type = checkType(type);     // Setter type, etter å ha processet den 
     health = 100;        // Health skal alltid starte som 100 
     maxCarry = valid.checkInt(setMaxWeight); // Sets max carry weight 
     currentWeight = 0;       // Start vekten til player 
     gold = valid.checkInt(goldValue);   // setter goldbeholding etter å ha sjekka at den ikke er negativ 
    } 

    /** 
    * En metode for å selge ett Item objekt, reduserer gold og øker weight ved kjøp. 
    * 
    * @param item  Item object to sell 
    */ 
    private void buyItem(Item item) 
    { 
     // Temporary values given from items methods getweight and getvalue to be used in a mutation 
     int tempWeight; 
     int tempValue; 
     tempWeight = item.getWeight(); 
     tempValue = item.getValue(); 
     // Checks if the item meets te conditions to be bought (enough gold, and can be carried) 
     if (checkConditions(tempValue, tempWeight)) { 
      // Adds the item to ArrayList if conditions met and updates gold and weight 
      items.add(item); 
      currentWeight += tempWeight; 
      gold -= tempValue; 
     } 
    } 

    /** 
    * Method to calculate if given value and weight is accepted to perform a purchase (total gold > 0 && total weight < maxWeight) 
    * 
    * @param value  Gold value of item 
    * @param weight Weight of item 
    * @return boolean Returns true if conditions met 
    */ 
    private boolean checkConditions(int value, int weight) 
    { 
     if (!(gold >= value)) 
     { 
      System.out.println("You don't have enough gold!"); 
      return false; 
     } else { 
      if (!(weight + currentWeight <= maxCarry)){ 
       System.out.println("You'll be too heavy carry this item!"); 
       return false; 
      } else { 
       // All conditions met 
       return true; 
      } 
     } 
    } 

    /** 
    * Adds an item to player inventory (uses method buyItem to process the item as a purchase) 
    * 
    * @param itemName String to name item 
    * @param itemDesc String to describe item 
    * @param itemValue int to declare items value 
    * @param itemWeight int to declare items Weight 
    * @param itemAction String to give item an action 
    */ 
    public void addItem(String itemName, String itemDesc, int itemValue, int itemWeight, String itemAction) 
    { 
     // A Player generated item, which needs all parameters to specify it 
     item = new Item(itemName, itemDesc, itemValue, itemWeight, itemAction); 
     buyItem(item); 
    } 

    /** 
    * Randomly generates a Sword object and adds it to players inventory (uses buyItem to process) 
    * @see Swords#Swords 
    */ 
    public void addSword() 
    { 
     sword = new Swords(); 
     buyItem(sword); 
    } 

    /** 
    * Randomly generates a Potion object and adds it to players inventory (uses buyItem to process) 
    * @see Potions#Potions 
    */ 
    public void addPotion() 
    { 
     potion = new Potions(); 
     buyItem(potion); 
    } 

Answer 1

您可以創建一個名爲Factory類的東西。工廠類的職責是爲您生成一種物品的實例。

https://www.tutorialspoint.com/design_pattern/factory_pattern.htm

基本上你換你的一類說說方法並返回該對象的新實例。

public class ItemFactory{ 

    public static Item addItem(String typeofItem){ 
     switch(typeofItem){ 
      case "Sword": 
       return new Sword(); 
      case "Potion": 
       return new Potion(); 
      ... 
      default: 
       //put any code here that is like the "else" of an if-else block 
       return null; 
     } 
    } 

} 

然後，當你需要添加特定類型的新項目：

buyItem(ItemFactory.addItem("Sword"));