Changes

Blocks must be [[Registration|registered]] to function.

Blocks must be [[Registration|registered]] to function.

{{Colored box|title=Important|content=A block in the world and a "block" in an inventory are very different things. A block in the world is represented by an <code><nowiki>BlockState</nowiki></code>, and its behavior defined by an instance of <code><nowiki>Block</nowiki></code>. Meanwhile, an item in an inventory is an <code><nowiki>ItemStack</nowiki></code>, controlled by an <code><nowiki>Item</nowiki></code>. As a bridge between the different worlds of <code><nowiki>Block</nowiki></code> and <code><nowiki>Item</nowiki></code>, there exists the class <code><nowiki>BlockItem</nowiki></code>. <code><nowiki>BlockItem</nowiki></code> is a subclass of <code><nowiki>Item</nowiki></code> that has a field <code><nowiki>block</nowiki></code> that holds a reference to the <code><nowiki>Block</nowiki></code> it represents. <code><nowiki>BlockItem</nowiki></code> defines some of the behavior of a "block" as an item, like how a right click places the block. It's possible to have a <code><nowiki>Block</nowiki></code> without an <code><nowiki>BlockItem</nowiki></code>. (E.g. <code><nowiki>minecraft:water</nowiki></code> exists as a block, but not an item. It is therefore impossible to hold it in an inventory as one.)

{{Tip/Important|A block in the world and a "block" in an inventory are very different things. A block in the world is represented by an <code><nowiki>BlockState</nowiki></code>, and its behavior defined by an instance of <code><nowiki>Block</nowiki></code>. Meanwhile, an item in an inventory is an <code><nowiki>ItemStack</nowiki></code>, controlled by an <code><nowiki>Item</nowiki></code>. As a bridge between the different worlds of <code><nowiki>Block</nowiki></code> and <code><nowiki>Item</nowiki></code>, there exists the class <code><nowiki>BlockItem</nowiki></code>. <code><nowiki>BlockItem</nowiki></code> is a subclass of <code><nowiki>Item</nowiki></code> that has a field <code><nowiki>block</nowiki></code> that holds a reference to the <code><nowiki>Block</nowiki></code> it represents. <code><nowiki>BlockItem</nowiki></code> defines some of the behavior of a "block" as an item, like how a right click places the block. It's possible to have a <code><nowiki>Block</nowiki></code> without an <code><nowiki>BlockItem</nowiki></code>. (E.g. <code><nowiki>minecraft:water</nowiki></code> exists as a block, but not an item. It is therefore impossible to hold it in an inventory as one.)

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When a block is registered, ''only'' a block is registered. The block does not automatically have an <code><nowiki>BlockItem</nowiki></code>. To create a basic <code><nowiki>BlockItem</nowiki></code> for a block, one should use <code><nowiki>new BlockItem(block)</nowiki></code> and match the registry name between the two objects. Custom subclasses of <code><nowiki>BlockItem</nowiki></code> may be used as well. Once a <code><nowiki>BlockItem</nowiki></code> has been registered for a block, <code><nowiki>Block#asItem</nowiki></code> can be used to retrieve it. <code><nowiki>Block#asItem</nowiki></code> will deafult to <code><nowiki>Items#AIR</nowiki></code> if there is no <code><nowiki>BlockItem</nowiki></code> for the <code><nowiki>Block</nowiki></code>, so if you are not certain that there is an <code><nowiki>BlockItem</nowiki></code> for the <code><nowiki>Block</nowiki></code> you are using, check for <code><nowiki>Items#AIR</nowiki></code>.}}

When a block is registered, ''only'' a block is registered. The block does not automatically have an <code><nowiki>BlockItem</nowiki></code>. To create a basic <code><nowiki>BlockItem</nowiki></code> for a block, one should use <code><nowiki>new BlockItem(block)</nowiki></code> and match the registry name between the two objects. Custom subclasses of <code><nowiki>BlockItem</nowiki></code> may be used as well. Once a <code><nowiki>BlockItem</nowiki></code> has been registered for a block, <code><nowiki>Block#asItem</nowiki></code> can be used to retrieve it. <code><nowiki>Block#asItem</nowiki></code> will deafult to <code><nowiki>Items#AIR</nowiki></code> if there is no <code><nowiki>BlockItem</nowiki></code> for the <code><nowiki>Block</nowiki></code>, so if you are not certain that there is an <code><nowiki>BlockItem</nowiki></code> for the <code><nowiki>Block</nowiki></code> you are using, check for <code><nowiki>Items#AIR</nowiki></code>.}}