How to use Reflector Class.cast() correctly?

Question

I am currently developing a Minecraft plugin that should be able to manage mobs. In short, in any case, I want my plugin to be a maximum multi-version, so I use Reflector. but when I use Class.cast(Object o) I get unwanted classes.

This is what I have without Reflector:

WorldServer nms = ((CraftWorld) entity.getWorld()).getHandle();
nms.addEntity((net.minecraft.server.v1_13_R2.Entity) ((CraftEntity) entity).getHandle(), SpawnReason.CUSTOM);

With Reflector:

try {
    // We get the craftworld class with nms so it can be used in multiple versions
    Class<?> craftWorldClass = getNMSClass("org.bukkit.craftbukkit.", "CraftWorld");

    // Cast the bukkit world to the craftworld
    Object craftWorldObject = craftWorldClass.cast(entity.getWorld());

    // Create variable with the method that get handle
    // https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/browse/src/main/java/org/bukkit/craftbukkit/CraftWorld.java#580
    Method getHandleMethod = craftWorldObject.getClass().getMethod("getHandle");

    // Attempt to invoke the method that creates the entity itself. This returns a net.minecraft.server entity
    Object worldServerObject = getHandleMethod.invoke(craftWorldObject);


    // We get the CraftEntity class
    Class<?> craftEntityClass = getNMSClass("org.bukkit.craftbukkit.", "entity.CraftEntity");

    //cast org.bukkit.entity.Entity to CraftEntity
    Object craftEntityObject = craftEntityClass.cast(entity);

    //get the method getHandle
    Method entityGetHandleMethod = craftEntityClass.getMethod("getHandle");

    //Attempt to invoke the method
    Object entityTypeObject = entityGetHandleMethod.invoke(craftEntityObject);

    // We get the Entity class of NMS
    Class<?> entityClass = getNMSClass("net.minecraft.server.", "Entity");

    System.out.println(entityClass);

    //cast CraftEntity to NMS Entity
    Object entityObject = entityClass.cast(entityTypeObject);

    System.out.println(entityTypeObject.getClass());
    System.out.println(entityObject.getClass());

    //get the method to add mob in world
    Method addEntityMethod = worldServerObject.getClass().getMethod("addEntity", entityClass, SpawnReason.CUSTOM.getClass());

    //Attempt to invoke the method
    addEntityMethod.invoke(entityObject, SpawnReason.CUSTOM);


} catch (ClassNotFoundException | NoSuchMethodException | InvocationTargetException | IllegalAccessException exception) {
    exception.printStackTrace();
}


private static Class<?> getNMSClass(String prefix, String nmsClassString) throws ClassNotFoundException {
    // Getting the version by splitting the package
    String version = Bukkit.getServer().getClass().getPackage().getName().replace(".", ",").split(",")[3] + ".";

    // Combining the prefix + version + nmsClassString for the full class path
    String name = prefix + version + nmsClassString;
    return Class.forName(name);
}

So in my logic I find myself at the output with an object of type NMS Entity, but in my tests I'm getting by with a NMS EntityZombie

Output:

[15:43:01 INFO]: class net.minecraft.server.v1_13_R2.Entity
[15:43:01 INFO]: class net.minecraft.server.v1_13_R2.EntityZombie
[15:43:01 INFO]: class net.minecraft.server.v1_13_R2.EntityZombie

So how do I use Reflector to get the right type?

Thx for your help ^^

Answer 1

ZombieEntity inherits from Entity indirectly (ZombieEntity -> EntityCreature -> EntityCreature -> EntityInsentient -> EntityLiving -> Entity), that means it is already an Entity.

You cast it, but the cast doesn't change the class type. Quick example:

String s = "This is a test";
Object obj = (Object) s;
System.out.println(obj.getClass().getName());
// prints "java.lang.String"

Your code is correct.