if(List.contains(new Object(int x, int y, int z))) Help!

Ok I need to make sure I don't have duplicate blocks in my list so I was using this method of adding blocks to a linkedList

PHP:

  protected void addBlock(int x,int y, int z){
    if(!blocks.contains(new pBlock(x,y,z)))
      blocks.add(new pBlock(x,y,z));
  }


Trying to not have duplicate block coordinates.
Does any one know what I am trying to do?

public class pBlock {
public int x;
public int y;
public int z;

public pBlock (int x, int y, int z) {
this.x = x;
this.y = y;
this.z = z;
}
}

 

Okey let me explain what your if-statement will do:

if(!blocks.contains(new pBlock(x,y,z)))

"Hey i just created a new object! Does the list contain this new object?"

The answer will always be false since that object was just created and obviously wasnt added prior the if-statement to the list.

In your adding statement below you are creating yet another pBlock instance. You are not storing a reference to an existing object. Instead, try to store a reference to the actual object like: "blocks.add(world.getBlockAt(x,y,z))"

Then you can call the "blocks.contains(world.getBlockAt(x,y,z))" to see if you have stored the block.

But BEWERE! Dont do this with alot of blocks! That way youll have a memory leak and a laggy server. Try to get it down to primitive data values and store those instead.

 

Thanks for the comment! I realized why this doesn't work but I was curious if there was a way to do this without using World.getBlockAt() because of overhead memory, that is why I am asking. Any other suggestions?

 

Except that would always return false because blocks doesn't contain Blocks, it contains pBlocks. I do agree with the new creation of an object thing though.

Prgr
I think your best bet is to check each int for equality in a for loop.

 

Add an equals() method to your pBlock object. Something like this:

Code:

@Override
public boolean equals(Object o) {
    if (o instanceof pBlock) {
        pBlock b = (pBlock)o;
        return b.x == this.x && b.y == this.y && b.z == this.z;
    }
    return false;
}

For efficiency, you should also only create a new object once:

Code:

  protected void addBlock(int x,int y, int z){
    pBlock b = new pBlock(x,y,z);
    if(!blocks.contains(b))
      blocks.add(b);
  }

 

Prgr you said "linked list" at the top of your post. Seriously, don't use a linked list for this, unless you really enjoy having your server telling you it can't keep up. contains() on any kind of List with a non-trivial number of elements isn't going to be efficient. Use a HashSet to hold your objects, and ensure you have a valid hashCode() method in your pBlock class. Eclipse can generate one for you (Source -> Generate hashCode() and equals()) and I'm sure other IDE's can too.