[1.14.4] NullPointer When Loading Capability Data

[unassigned]

Hello,

 

I've recently started modding again so I'm still fairly new to the 1.13 changes.

As capabilities have changed somewhat, I'm getting stuck trying to read/write the cap data when the player first joins: I get a NullPointer when I first login after the capability gets attached. Meaning, the first login works, but any following attempts fail will crash:

net.minecraft.crash.ReportedException: Loading entity NBT
	at net.minecraft.network.NetworkSystem.tick(NetworkSystem.java:154) ~[?:?] {re:classloading}
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:882) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:800) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:646) [?:?] {re:classloading,pl:accesstransformer:B}
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_231] {}
Caused by: java.lang.NullPointerException
	at net.minecraftforge.fml.network.PacketDistributor.lambda$playerConsumer$1(PacketDistributor.java:216) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.PacketDistributor$PacketTarget.send(PacketDistributor.java:178) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.simple.SimpleChannel.send(SimpleChannel.java:118) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.impl.PlayerVoid.setVoidStored(PlayerVoid.java:61) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.PlayerVoidStorage.readNBT(PlayerVoidStorage.java:37) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.PlayerVoidStorage.readNBT(PlayerVoidStorage.java:10) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.PlayerVoidProvider.deserializeNBT(PlayerVoidProvider.java:39) ~[?:?] {re:classloading,pl:capability_inject_definalize:A}
	at com.unassigned.voidmagic.common.capability.playervoid.PlayerVoidProvider.deserializeNBT(PlayerVoidProvider.java:15) ~[?:?] {re:classloading,pl:capability_inject_definalize:A}
	at net.minecraftforge.common.capabilities.CapabilityDispatcher.deserializeNBT(CapabilityDispatcher.java:139) ~[?:?] {re:classloading}
	at net.minecraftforge.common.capabilities.CapabilityProvider.deserializeCaps(CapabilityProvider.java:96) ~[?:?] {re:classloading}
	at net.minecraft.entity.Entity.read(Entity.java:1656) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.management.PlayerList.readPlayerDataFromFile(PlayerList.java:269) ~[?:?] {re:classloading}
	at net.minecraft.server.management.PlayerList.initializeConnectionToPlayer(PlayerList.java:112) ~[?:?] {re:classloading}
	at net.minecraft.network.login.ServerLoginNetHandler.tryAcceptPlayer(ServerLoginNetHandler.java:119) ~[?:?] {re:classloading}
	at net.minecraft.network.login.ServerLoginNetHandler.tick(ServerLoginNetHandler.java:63) ~[?:?] {re:classloading}
	at net.minecraft.network.NetworkManager.tick(NetworkManager.java:241) ~[?:?] {re:classloading}
	at net.minecraft.network.NetworkSystem.tick(NetworkSystem.java:148) ~[?:?] {re:classloading}
	... 5 more

 

I should also add that it does not crash when I send the packet through other means. I do have some idea to what is causing this crash, however: the packet to update the server w/ the client is being sent while the client is not actually connected yet. I found this result through checking if the client is connected before syncing the data, however this leads to the values not being synced once the NBT is set. I just have no idea on how to fix this problem.

 

Here is the code that is within the stacktrace, and here is my github if you need to see anything else.

 

PlayerVoidStorage (Capability Storage Class):

  Reveal hidden contents

package com.unassigned.voidmagic.common.capability.playervoid;

import net.minecraft.nbt.CompoundNBT;
import net.minecraft.nbt.INBT;
import net.minecraft.util.Direction;
import net.minecraftforge.common.capabilities.Capability;

import javax.annotation.Nullable;

public class PlayerVoidStorage implements Capability.IStorage<IPlayerVoid> {
    @Nullable
    @Override
    public INBT writeNBT(Capability<IPlayerVoid> capability, IPlayerVoid instance, Direction side) {
        CompoundNBT compound = new CompoundNBT();
        if(capability != null && instance != null) {
            if(instance.getAttachedPlayer() != null) {
                compound.putInt("VoidStored", instance.getVoidStored());

                CompoundNBT skillCompound = new CompoundNBT();
                for(IVoidSkill skill : instance.getVoidSkills()) {
                    if(skill != null){ //fallback check
                        skillCompound.putInt("Skill#"+skill.skillID(), skill.skillID());
                    }
                }
                compound.put("VoidSkills", skillCompound);
            }
        }
        return compound;
    }

    @Override
    public void readNBT(Capability<IPlayerVoid> capability, IPlayerVoid instance, Direction side, INBT nbt) {
        if(capability != null && instance != null && nbt != null) {
            if(nbt instanceof CompoundNBT) {
                CompoundNBT compound = (CompoundNBT)nbt;
                if(compound.contains("VoidStored")) {
                    instance.setVoidStored(compound.getInt("VoidStored"));
                }
                if(compound.contains("VoidSkills")){
                    // -- TODO -- \\
                }
            }
        }
    }
}

 

 

PlayerVoidProvider (Capability Provider Class):

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package com.unassigned.voidmagic.common.capability.playervoid;

import com.unassigned.voidmagic.common.capability.playervoid.impl.PlayerVoid;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.nbt.CompoundNBT;
import net.minecraft.util.Direction;
import net.minecraftforge.common.capabilities.Capability;
import net.minecraftforge.common.capabilities.CapabilityInject;
import net.minecraftforge.common.capabilities.ICapabilitySerializable;
import net.minecraftforge.common.util.LazyOptional;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

public class PlayerVoidProvider implements ICapabilitySerializable<CompoundNBT> {

    @CapabilityInject(IPlayerVoid.class)
    public static final Capability<IPlayerVoid> CAPABILITY_PLAYER_VOID = null;

    private final LazyOptional<IPlayerVoid> instance;

    public PlayerVoidProvider(PlayerEntity player) { instance = LazyOptional.of(() -> new PlayerVoid(player)); }

    @Nonnull
    @Override
    public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap, @Nullable Direction side) {
        if(cap != CAPABILITY_PLAYER_VOID) return LazyOptional.empty();
        return this.instance.cast();
    }

    @Override
    public CompoundNBT serializeNBT() {
        return (CompoundNBT)(CAPABILITY_PLAYER_VOID.getStorage()
                .writeNBT(CAPABILITY_PLAYER_VOID,
                        instance.orElseThrow(()->new IllegalArgumentException("Invalid LazyOptional!")),
                        null));
    }

    @Override
    public void deserializeNBT(CompoundNBT nbt) {
        CAPABILITY_PLAYER_VOID.getStorage().readNBT(CAPABILITY_PLAYER_VOID,
                instance.orElseThrow(()->new IllegalArgumentException("Invalid LazyOptional!")),
                null, nbt);
    }

    public static IPlayerVoid getPlayerVoid(PlayerEntity playerEntity) {
        return playerEntity.getCapability(CAPABILITY_PLAYER_VOID, null).orElseThrow(() -> new IllegalArgumentException("Invalid Target!"));
    }
}

 

 

PlayerVoid (impl of IPlayerVoid):

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package com.unassigned.voidmagic.common.capability.playervoid.impl;

import com.unassigned.voidmagic.VoidMagic;
import com.unassigned.voidmagic.common.capability.playervoid.IVoidSkill;
import com.unassigned.voidmagic.common.capability.playervoid.IPlayerVoid;
import com.unassigned.voidmagic.network.messages.MessagePlayerVoid;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.entity.player.ServerPlayerEntity;
import net.minecraftforge.fml.network.PacketDistributor;

import javax.annotation.Nonnull;
import java.util.ArrayList;

public class PlayerVoid implements IPlayerVoid {

    protected final PlayerEntity player;

    protected ArrayList<IVoidSkill> voidSkills;
    protected int voidStored;

    public PlayerVoid(PlayerEntity player) {
        this.player = player;
        this.voidStored = 0;
        this.voidSkills = new ArrayList<>();
    }

    @Override
    public PlayerEntity getAttachedPlayer() {
        return this.player;
    }

    @Override
    public ArrayList<IVoidSkill> getVoidSkills() {
        return this.voidSkills;
    }

    @Override
    public void setVoidSkills(ArrayList<IVoidSkill> set) {
        this.voidSkills = set;
    }

    @Override
    public void addSkill(@Nonnull IVoidSkill skill) {
        if(!this.voidSkills.contains(skill)) this.voidSkills.add(skill);
    }

    @Override
    public void removeSkill(IVoidSkill skill) {
        this.voidSkills.remove(skill);
    }

    @Override
    public int getVoidStored() {
        return this.voidStored;
    }

    @Override
    public void setVoidStored(int set) {
        this.voidStored = set;
        if(player != null && !player.world.isRemote)
            VoidMagic.network.send(PacketDistributor.PLAYER.with(()-> (ServerPlayerEntity) player), new MessagePlayerVoid(this.voidStored));
    }

    @Override
    public void addVoid(int toAdd) {
        this.voidStored += toAdd;
        if(player != null && !player.world.isRemote)
            VoidMagic.network.send(PacketDistributor.PLAYER.with(()-> (ServerPlayerEntity) player), new MessagePlayerVoid(this.voidStored));
    }

    @Override
    public void removeVoid(int removeVoid) {
        if(this.voidStored - removeVoid < 0){ this.voidStored = 0; }
            else { this.voidStored -= removeVoid; }

        if(player != null && !player.world.isRemote)
            VoidMagic.network.send(PacketDistributor.PLAYER.with(()-> (ServerPlayerEntity) player), new MessagePlayerVoid(this.voidStored));
    }

    @Override
    public int getMaxVoidStored() {
        return 100000;
    }

}

 

 

[Cadiboo]

You should have a reference to your actual capability and only use/provide your LazyOptional for external operations.

[unassigned]

  On 1/7/2020 at 2:21 AM, Cadiboo said:

You should have a reference to your actual capability and only use/provide your LazyOptional for external operations.

Expand  

Yeah, I just needed some clarification on the new LazyOptional system, as I'm still not too sure what/when to use them. So doing something like this:

                e.getCapability(PlayerVoidProvider.CAPABILITY_PLAYER_VOID).ifPresent(pv -> pv.setVoidStored(message.playerVoid));

isn't correct? Or am I mistaking what you are meaning.

 

[Cadiboo]

If you know that the object exists and have access to it, you shouldn’t be using an optional. An Optional should be exposed to the rest of the world with getCapability BUT you know that your capability will never be null so you should use a direct reference in your internal code.

[unassigned]

  On 1/7/2020 at 5:16 AM, Cadiboo said:

If you know that the object exists and have access to it, you shouldn’t be using an optional. An Optional should be exposed to the rest of the world with getCapability BUT you know that your capability will never be null so you should use a direct reference in your internal code.

Expand  

Ok. I think I see what you are meaning, however I still don't exactly see where I'm doing anything wrong. I know when I get the capability to send the packet that the cap isn't ever null, so direct reference is fine in this case I believe.

[unassigned]

I believe I went through and changed what needed to be changed, but I still get the same error. I did quite the rewrite to get everything in order again, and just for optimization purposes. Here is the stacktrace again:

  Reveal hidden contents

[19:43:13] [Server thread/ERROR] [minecraft/MinecraftServer]: Encountered an unexpected exception
net.minecraft.crash.ReportedException: Loading entity NBT
	at net.minecraft.network.NetworkSystem.tick(NetworkSystem.java:154) ~[?:?] {re:classloading}
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:882) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:800) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:646) [?:?] {re:classloading,pl:accesstransformer:B}
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_231] {}
Caused by: java.lang.NullPointerException
	at net.minecraftforge.fml.network.PacketDistributor.lambda$playerConsumer$1(PacketDistributor.java:216) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.PacketDistributor$PacketTarget.send(PacketDistributor.java:178) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.simple.SimpleChannel.send(SimpleChannel.java:118) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.impl.PlayerVoid.onVoidChanged(PlayerVoid.java:86) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.impl.PlayerVoid.setVoidStored(PlayerVoid.java:60) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.CapabilityPlayerVoid$1.readNBT(CapabilityPlayerVoid.java:50) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.playervoid.CapabilityPlayerVoid$1.readNBT(CapabilityPlayerVoid.java:23) ~[?:?] {re:classloading}
	at net.minecraftforge.common.capabilities.Capability.readNBT(Capability.java:104) ~[?:?] {re:classloading}
	at com.unassigned.voidmagic.common.capability.CapabilityProviderSerializable.deserializeNBT(CapabilityProviderSerializable.java:65) ~[?:?] {re:classloading}
	at net.minecraftforge.common.capabilities.CapabilityDispatcher.deserializeNBT(CapabilityDispatcher.java:139) ~[?:?] {re:classloading}
	at net.minecraftforge.common.capabilities.CapabilityProvider.deserializeCaps(CapabilityProvider.java:96) ~[?:?] {re:classloading}
	at net.minecraft.entity.Entity.read(Entity.java:1656) ~[?:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.server.management.PlayerList.readPlayerDataFromFile(PlayerList.java:269) ~[?:?] {re:classloading}
	at net.minecraft.server.management.PlayerList.initializeConnectionToPlayer(PlayerList.java:112) ~[?:?] {re:classloading}
	at net.minecraft.network.login.ServerLoginNetHandler.tryAcceptPlayer(ServerLoginNetHandler.java:119) ~[?:?] {re:classloading}
	at net.minecraft.network.login.ServerLoginNetHandler.tick(ServerLoginNetHandler.java:63) ~[?:?] {re:classloading}
	at net.minecraft.network.NetworkManager.tick(NetworkManager.java:241) ~[?:?] {re:classloading}
	at net.minecraft.network.NetworkSystem.tick(NetworkSystem.java:148) ~[?:?] {re:classloading}
	... 5 more

Note that this crash happens around just before the player finishes connecting after leaving with nbt data saved.

 

Here are some direct links to the proper github files, as those will house the lines where everything is happening.

CapabilityPlayerVoid

PlayerVoid

MessagePlayerVoid

 

Thank you both for your help so far.

[unassigned]

  On 1/8/2020 at 9:17 AM, diesieben07 said:

You are trying to send a packet while being read from NBT. That does not work, the player doesn't exist fully yet, so you can't send a packet to it.

Expand  

Ah gotcha. I did the following, which is quite hacky but seems to work: I added a parameter to the setVoidStored to send the packet or not, then send the packet when the entity joins the world.

 

new readNBT within the cap:

                            instance.setVoidStored(compound.getInt("VoidStored"), false);

 

new event to send the packet after the player is done connecting:

    @SubscribeEvent
    public void onJoinWorld(EntityJoinWorldEvent event) {
        Entity e = event.getEntity();
        if(e != null) {
            if(e instanceof PlayerEntity) {
                CapabilityPlayerVoid.getPlayerVoid((PlayerEntity)e).ifPresent(IPlayerVoid::onVoidChanged);
            }
        }
    }

 

Let me know if there is a simpler way of doing it. Other than that thanks for your help!