CODEWITHSUNDEEP
javaclasshashmap
SubarakiThePepsi
SubarakiThePepsi

Reputation: 11

Creating a new instance from a class stored in a hashmap

I'm stuck on a problem with creating a new instance from a stored class in an hashmap.

I'm doing : saving an instance of a class to a hashmap as referal to load classes from by UIN (unique item name) ((which is a string))

problem : the instance saved stays the same, resulting in placing the same instance for every block saved, which results in only one block being replaced when a save is loaded.

looking for : how would i create a new instance so i can place all my blocks properly back ?

Code :

Registering:

/*======================Registry===========================*/
public static HashMap<String, Block> registeredBlocks = new HashMap<String, Block>();

public static void registerBlock(Block block){
    registeredBlocks.put(block.getUIN(), block);
}

public static void loadBlocks(){
    registerBlock(new BlockChest());
    registerBlock(new BlockTree());

    System.out.println(registeredBlocks);
    System.out.println(registeredBlocks.containsKey("chestBlock"));
    System.out.println(registeredBlocks.get("chestBlock"));
    System.out.println(Blocks.chest);
}

public static Block getBlockFromUIN(String uin){
    if(registeredBlocks.containsKey(uin)){
        return registeredBlocks.get(uin);
    }
    return null;
}

Reference

public static BlockChest chest = (BlockChest)Block.registeredBlocks.get("chestBlock");
public static BlockTree log = (BlockTree)Block.registeredBlocks.get("treeLog");

Upvotes: 0

Views: 2270

Answers (1)

drew moore
drew moore

Reputation: 32680

You're not storing classes in your hashmap: 

HashMap<String, Block> registeredBlocks

This is mapping Strings to Block instances, hence the behavior you're observing.

Instead: 

HashMap<String, Class> registeredBlocks

will store Class objects 

registeredBlocks.put(block.getUIN(), block.getClass());  //or Block.class

will put the Block class to your map with whatever the key String is, and

Block b = (Block)registeredBlocks.get(keyString).newInstance();

will give you a new instance of that class, cast to Block.

Note 1: this is utilizing the Class.newInstance() method.

Note 2: This is meant purely as an answer to your question. What you're trying to do is not immediately apparent in your post, but I'm fairly confident there's a cleaner/better way to achieve what you're trying to achieve.

Upvotes: 2

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