Hello,

 

First how can I create like a listener to check the block where the player is standing on?

Second how can I make (example) if the player health is between 0 and 5 the player starts dropping the item that he has in his hands?

 

 

Thanks, Joao Lourenco.

how can I?

Try to search with a TileEntity for the Players within AABB like for example the beacon does an then make an Iterator to go through the player list and get their current health.

Here is what I put together for you:

AxisAlignedBB axisalignedbb = AxisAlignedBB.getBoundingBox(this.xCoord, this.yCoord+1, this.zCoord, this.xCoord+1, this.yCoord+3, this.zCoord+1);
entityList = this.worldObj.getEntitiesWithinAABB(EntityPlayer.class, axisalignedbb);
Iterator iterator = entityList.iterator();
EntityPlayer entity;

while (iterator.hasNext()) {
    entity = iterator.next();
    if (entity.getHealth < 5) {
        //DO Your stuff
    }
}

this should work for you.

Using a tile entity?  Ew, that's an awful way to do it.

 

//EventHandler.java
@ForgeSubscribe
    public void EntityUpdate(LivingEvent event){
        if (entity instanceof EntityPlayer && entity.getHealth < 5) {
            //DO Your stuff
        }
    }

//base mod.java
MinecraftForge.EVENT_BUS.register(new EventHandler());

Oh?

I didn't knew about that.

But that wouldn't work with a longer Range.