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Using IExtendedEntityProperties on multiplayer


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Hello, I'm trying to use a class that implements IExtendedEntityProperties to add a currency to the player. I initialize the class when the player entity is constructed like so:

@ForgeSubscribe(priority = EventPriority.NORMAL)
public void onEntityConstuct(EntityConstructing event) {
	if (event.entity instanceof EntityPlayerMP) {
		EntityPlayerMP ep = (EntityPlayerMP) event.entity;
		ep.registerExtendedProperties(PlayerProperties.IDENTIFIER, new PlayerProperties());


The PlayerProperties class looks like so:

public class PlayerProperties implements IExtendedEntityProperties {

public static final String IDENTIFIER = "playerproperties";

public static PlayerProperties fromPlayer(EntityPlayerMP player) {
	return (PlayerProperties) player.getExtendedProperties(IDENTIFIER);

int credits = 0;

EntityPlayerMP player;

public void saveNBTData(NBTTagCompound compound) {
	compound.setInteger("credits", credits);

public void loadNBTData(NBTTagCompound compound) {
	if (compound.hasKey("credits")) {
		this.credits = compound.getInteger("credits");
	} else {
		this.credits = 30;

public void init(Entity entity, World world) {
	player = (EntityPlayerMP) entity;

private void sendPacket() {
	PacketDispatcher.sendPacketToPlayer(new PropertiesPacket(credits).makePacket(), (Player) player);


Where my PropertiesPacket class looks like so:

public class PropertiesPacket extends BasePacket {

int credits;

public PropertiesPacket(int credits) {
	this.credits = credits;

public PropertiesPacket() {


public void write(ByteArrayDataOutput out) {

public void read(ByteArrayDataInput in) {
	credits = in.readInt();

public void execute(EntityPlayer player, Side side) {
	if (side.isClient()) {
		PlayerData.credits = credits; // PlayerData is just a static client side class which stores the data.



Where the BasePacket class looks like this:

public abstract class BasePacket {

public static final String CHANNEL = "MyPacket";
private static final BiMap<Integer, Class<? extends BasePacket>> idMap;

static {
	ImmutableBiMap.Builder<Integer, Class<? extends BasePacket>> builder = ImmutableBiMap.builder();

	builder.put(Integer.valueOf(0), PropertiesPacket.class);

	idMap = builder.build();

public static BasePacket constructPacket(int packetId) throws ProtocolException, ReflectiveOperationException {
	Class<? extends BasePacket> clazz = idMap.get(Integer.valueOf(packetId));
	if (clazz == null) {
		throw new ProtocolException("Unknown Packet Id!");
	} else {
		return clazz.newInstance();

public static class ProtocolException extends Exception {

	public ProtocolException() {

	public ProtocolException(String message, Throwable cause) {
		super(message, cause);

	public ProtocolException(String message) {

	public ProtocolException(Throwable cause) {

public final int getPacketId() {
	if (idMap.inverse().containsKey(getClass())) {
		return idMap.inverse().get(getClass()).intValue();
	} else {
		throw new RuntimeException("Packet " + getClass().getSimpleName() + " is missing a mapping!");

public final Packet makePacket() {
	ByteArrayDataOutput out = ByteStreams.newDataOutput();
	return PacketDispatcher.getPacket(CHANNEL, out.toByteArray());

public abstract void write(ByteArrayDataOutput out);

public abstract void read(ByteArrayDataInput in);

public abstract void execute(EntityPlayer player, Side side);


and my packet handler is as so:

public class PacketHandler implements IPacketHandler {

public void onPacketData(INetworkManager manager, Packet250CustomPayload packet, Player player) {
	try {
		EntityPlayer entityPlayer = (EntityPlayer) player;
		ByteArrayDataInput in = ByteStreams.newDataInput(packet.data);
		int packetId = in.readUnsignedByte();
		BasePacket basePacket = BasePacket.constructPacket(packetId);
		basePacket.execute(entityPlayer, entityPlayer.worldObj.isRemote ? Side.CLIENT : Side.SERVER);
	} catch (ProtocolException e) {
		if (player instanceof EntityPlayerMP) {
			((EntityPlayerMP) player).playerNetServerHandler.kickPlayerFromServer("Protocol Exception!");
			Logger.getLogger("DemoMod").warning("Player " + ((EntityPlayer) player).username + " caused a Protocol Exception!");
	} catch (ReflectiveOperationException e) {
		throw new RuntimeException("Unexpected Reflection exception during Packet construction!", e);

However, when this code is run, it throws a null pointer exception and the packet isn't sent. Every time I've used this method of sending packets previously it's worked a charm, but this time it doesn't.


The stack trace is:

2013-09-11 21:30:37 [iNFO] [sTDERR] java.lang.NullPointerException
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at cpw.mods.fml.common.network.PacketDispatcher.sendPacketToPlayer(PacketDispatcher.java:45)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at mods.SaberMod.SaberValues.sendPacket(SaberValues.java:147)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at mods.SaberMod.SaberValues.loadNBTData(SaberValues.java:76)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.entity.Entity.readFromNBT(Entity.java:1647)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.management.ServerConfigurationManager.readPlayerDataFromFile(ServerConfigurationManager.java:239)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.management.ServerConfigurationManager.initializeConnectionToPlayer(ServerConfigurationManager.java:113)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.integrated.IntegratedServerListenThread.networkTick(IntegratedServerListenThread.java:97)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:689)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:585)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:129)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:482)
2013-09-11 21:30:37 [iNFO] [sTDERR] 	at net.minecraft.server.ThreadMinecraftServer.run(ThreadMinecraftServer.java:16)


which points to this line in the packet dispatcher:

public static void sendPacketToPlayer(Packet packet, Player player)
        if (player instanceof EntityPlayerMP)
            ((EntityPlayerMP)player).playerNetServerHandler.sendPacketToPlayer(packet); //<-- this one

This suggests the player in its own variables is wrong, the player's missing the server handler or the packet is null. I'm assuming the packet is null, but I don't see why this one shouldn't work while the others do. What is the likely problem here?

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