I am creating a simple enemy that attacks the player, but I cannot make him actually deal damage to the player. All he does is run towards the player and make contact with him. No damage is dealt.

 

Code:

    public EntitySpecGhost(World worldIn)
    {
        super(worldIn);
        this.setSize(1, 2.4f);
    }

    @Override
    protected void initEntityAI()
    {
        tasks.addTask(0, new EntityAISwimming(this));
        tasks.addTask(1, new EntityAIAttackMelee(this, 2, true));
        tasks.addTask(2, new EntityAILookIdle(this));
        tasks.addTask(3, new EntityAIWatchClosest(this, EntityPlayer.class, 100));
        tasks.addTask(4, new EntityAIWander(this, 1));
        targetTasks.addTask(0, new EntityAIHurtByTarget(this, true));
    }

    @Override
    protected void applyEntityAttributes()
    {
        super.applyEntityAttributes();
        getEntityAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).setBaseValue(15);
    }
    @Nullable
    @Override
    protected SoundEvent getHurtSound(DamageSource damageSourceIn)
    {
        return null;
    }

    @Nullable
    @Override
    protected SoundEvent getDeathSound()
    {
        return null;
    }

    @Override
    protected void playStepSound(BlockPos pos, Block blockIn)
    {
    }

 

I have a tutorial on this. http://jabelarminecraft.blogspot.com/p/minecraft-forge-1721710-custom-entity.html?m=1

 

The problem is usually you haven't properly overridden the attack as mob method, depending on what class you extended.