So, as stated, my custom entity does not attack others as specified.

I have heard that the entity has to override some thing. Is that true?

 

this.tasks.addTask(1, new EntityAIAttackOnCollide(this, EntityMob.class, 1, true));

So this line tells the entity to attack Mobs right?

I have a tutorial on this as it is a common problem: http://jabelarminecraft.blogspot.com/p/minecraft-forge-1721710-custom-entity.html

 

Hopefully one of the tips there will solve your problem.

so yeah u have that AI but it still wont attack unless you are specific about what mob you want it to attack plus, if you are extending off a type golem or something you might want to use this to make the mob attack.

 public boolean attackEntityAsMob(Entity entity)
    {
        this.worldObj.setEntityState(this, (byte)4);
        boolean flag = entity.attackEntityFrom(DamageSource.causeMobDamage(this), (float)(10 + this.rand.nextInt(15)));

    }

 

also look into irongolem code or vanilla code

Well, I have tried these items, but still I cant get the entity to attack others.

Also they disappear when the world is reloaded.

 

Entity Class:

http://pastebin.com/S7R4dYdj

dude how are you spawning it? if your not spawning it serverside then it wont work.