I am making a mod that causes an action occur, usually a chat message appears, when the player clicked a modded Item a made when clicking the left button.

 

I know how to do an action on the right mouse button, but how does one do it on the left mouse, especially if there might not be a block or entity when ever it clicks.

Last I checked there wasn't any generic left click method in the Item class, but you can subscribe to the ClientTickEvent and check if the GameSettings#keyBindAttack was pressed and your item is held, then call a method. Note that this is all CLIENT side, so if you want to do anything real, you'll need to send a packet to the server and do it there.

 

PlayerInteractEvent may also work, but I don't recall whether there is a LEFT_CLICK_AIR; if there is, you probably still need to send a packet, as I doubt it is called server side.

 

If you plan on having more than one item with this type of interaction, I'd make an interface for it such as ILeftClick with a method #onLeftClick, then you can have one check for that type of Item rather than a bunch of if/else if statements for all the different item types you want to handle.

I am also trying to do stuff on left click, here is what I have:

        @SideOnly(Side.CLIENT)
@SubscribeEvent
public void LeftClick(ClientTickEvent event)
{
	//LogHelper.info("At least I get called");
	if(Minecraft.getMinecraft().gameSettings.keyBindAttack.isPressed())
	{
		LogHelper.info("Attacking");
                }
        }

 

When the first LogHelper is uncommented it spams the log, so I know this method is getting called, but the second LogHelper never gets called. Any idea what I have wrong with this if statement?

You need to use #getKeyIsPressed, not #isPressed (at least in 1.8 it was that way). Also, TickEvents have both a Start and an End phase and you only want to choose one of them:

// example shortcut to only handle the start phase (in pseudo-code)
if (event.phase == end) {
  return;
}
rest of code;

Forgot about the event phase, but I cant find a getKeyIsPressed anywhere(I am in 1.8.9) I switched to isKeyDown and that seems to be working how I want it to.