[英]Zuul Remake in Java HashMap Issue
I am doing a piece of coursework in Java using BlueJ. 我正在使用BlueJ在Java中完成一部分课程。 We need to add new features to the text based game, Zuul. 我们需要为基于文本的游戏Zuul添加新功能。 I have decided to start working on an inventory and item system. 我决定开始研究库存和物料系统。 I am having trouble working out the best way to do this so I just winged it. 我在寻找最好的方法时遇到了麻烦,所以我只管了一下。 Here is my code. 这是我的代码。 Sorry I haven't gotten round to commenting everything yet. 抱歉,我还没有发表评论。 The game compiles but I get an exception in the console when I run the game. 游戏可以编译,但是运行游戏时控制台出现异常。
Error: 错误:
java.lang.NullPointerException
at Game.createPlayer(Game.java:15)
at Game.<init>(Game.java:7)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at bluej.runtime.ExecServer$3.run(ExecServer.java:740)
Game Class (This is equivalent of the Main class in Java, this is where the game is run from): 游戏类(与Java中的Main类等效,这是运行游戏的来源):
import java.util.*;
public class Game
{
public Game()
{
createPlayer();
createItems();
}
private Entity localPlayer;
public void createPlayer(){
Player localPlayer = new Player("Player Name", 0, 0, 0, 0, 0);
localPlayer.equipArmour("Helm", armourDB.get("Helm")); // This is where I think I have gone wrong
}
// Create global hashmap variables
private HashMap<String, Weapon> weaponsDB;
private HashMap<String, Armour> armourDB;
private HashMap<String, Supplement> supplementDB;
public void createItems(){
// Create weapons
weaponsDB = new HashMap<String, Weapon>();
Weapon weaponFists = new Weapon("Fists", "Weapon", 0, 0, 0, 0, 0, "Melee");
Weapon weaponSword = new Weapon("Sword", "Weapon", 0, 0, 0, 0, 0, "Melee");
Weapon weaponBow = new Weapon("Bow", "Weapon", 0, 0, 0, 0, 0, "Ranged");
Weapon weaponDagger = new Weapon("Dagger", "Weapon", 0, 0, 0, 0, 0, "Melee");
weaponsDB.put("Fists", weaponFists);
weaponsDB.put("Sword", weaponSword);
weaponsDB.put("Bow", weaponBow);
weaponsDB.put("Dagger", weaponDagger);
// Create armour
armourDB = new HashMap<String, Armour>();
Armour armourBreastplate = new Armour("Breatplate", "Chest", 0, 0, 0, 0, 0);
Armour armourHelm = new Armour("Helm", "Head", 0, 0, 0, 0, 0);
armourDB.put("Breastplate", armourBreastplate);
armourDB.put("Helm", armourHelm);
// Create supplements
supplementDB = new HashMap<String, Supplement>();
Supplement supplementHealthPotion = new Supplement("Health Potion", 0, 0);
Supplement supplementPowerPotion = new Supplement("Power Potion", 0, 0);
supplementDB.put("Health Potion", supplementHealthPotion);
supplementDB.put("Power Potion", supplementPowerPotion);
}
}
Entity Class (Construction for the player class and enemy class): 实体类(玩家类和敌人类的构造):
import java.util.*;
public class Entity
{
private boolean entityStatus;
private String entityName;
private int entityHealth;
private int entityPower;
private int entityHealthRegen;
private int entityPowerRegen;
private int entityAttackPower;
private HashMap<String, Armour> entityEquipment;
private ArrayList<Item> entityInventory;
public Entity(
String paramEntityName,
int paramEntityHealth,
int paramEntityPower,
int paramEntityHealthRegen,
int paramEntityPowerRegen,
int paramEntityAttackPower)
{
entityStatus = true;
entityName = paramEntityName;
entityHealth = paramEntityHealth;
entityPower = paramEntityPower;
entityHealthRegen = paramEntityHealthRegen;
entityPowerRegen = paramEntityPowerRegen;
entityAttackPower = paramEntityAttackPower;
entityEquipment = new HashMap<String, Armour>(); // Set all possible equipment slots to null on initial run
entityEquipment.put("Head", null);
entityEquipment.put("Shoulders", null);
entityEquipment.put("Chest", null);
entityEquipment.put("Hands", null);
entityEquipment.put("Legs", null);
entityEquipment.put("Feet", null);
entityEquipment.put("Weapon", null);
entityInventory = new ArrayList<Item>();
}
public boolean getEntityStatus(){
return entityStatus;
}
public String getEntityName(){
return entityName;
}
public int getEntityHealth(){
return entityHealth;
}
public int getEntityPower(){
return entityPower;
}
public int getEntityHealthRegen(){
return entityHealthRegen;
}
public int getEntityPowerRegen(){
return entityPowerRegen;
}
public int getEntityAttackPower(){
return entityAttackPower;
}
// Equips the player with an item into the equipment slot
public void equipArmour(String paramEquipmentSlot, Armour paramArmourName){
entityEquipment.put(paramEquipmentSlot, paramArmourName);
}
public void printInventory(){
System.out.println("Something");
}
}
I think the main problem is that I cannot wrap my head around the use of hashtags, I need to see a live example to see how it works. 我认为主要的问题是我无法全神贯注地使用井号,我需要看一个实时示例以了解其工作原理。 Can anyone help? 有人可以帮忙吗? If you need anything else from me, let me know. 如果您还需要我提供其他任何信息,请告诉我。
Well this is the problem: 好吧,这就是问题所在:
armourDB.get("Helm")
You haven't initialized armourDB
at that point. 此时您尚未初始化armourDB
。 If you call createItems()
before createPlayer()
it should be okay for that particular line. 如果在createPlayer()
createItems()
之前调用createItems()
,则对于该特定行应该没问题。 But you still won't be initializing the isntance variable called localPlayer
. 但是您仍然不会初始化名为localPlayer
的istance变量。 You'll only be assigning a value to the local variable declared in createPlayer
. 您将只为createPlayer
声明的局部变量赋值。
It's not really clear what you're trying to achieve to be honest, but those are the first two problems... 坦白说,您目前还不清楚要达到的目标,但这是前两个问题...
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