Extending the item class

Extending the Item class:

public class MyItem extends Item {
    public MyItem(Identifier id) {
        super(id, Material.PAPER);
        createTooltip(tooltip);
        updateTooltip();
    }
    
    @Override
    public void createTooltip(Tooltip tooltip) {
        tooltip.lines.clear();
        tooltip.addLine(Component.text("Sends a message whenever a block is broken!"));
    }
    
    @Override
    public ActionResult postMine(LivingEntity source, Block target) {
        source.sendMessage(Component.text("You broke a Block!"));
        return ActionResult.PASS;
    }
}

then you have to register it like this:

ITEMS.register("my_item", MyItem::new);

There are other methods that you can override:

ActionResult postHit(LivingEntity source, Entity target
ActionResult onUseOn(UseContext ctx)
void onUse(LivingEntity source, EquipmentSlot hand)
void onCraftedBy(Player player)

03 October 2025