Every time you restart the game or re-enter the map, the capability is reset. I don’t know if this is a problem with my code or is it the way it is.

public class CapabilityAttachHandler {
    public CapabilityAttachHandler() {}

    public static void capabilityAttachHandler(AttachCapabilitiesEvent<Entity> event) {
        Entity entity = event.getObject();
        if (entity instanceof PlayerEntity){
            if (!entity.getCapability(LibCapabilities.MIND_CAPABILITY).isPresent()) {
                event.addCapability(SaintChapter.key("mind_strength"), new MindCapabilityProvider());
                SaintChapter.LOGGER.info("Mind Capability attached");
            }
            if (!entity.getCapability(LibCapabilities.SOUL_CAPABILITY).isPresent()){
                event.addCapability(SaintChapter.key("soul_strength"), new SoulCapabilityProvider());
                SaintChapter.LOGGER.info("Player Soul Capability attached");
            }
        }
        if (entity instanceof MobEntity) {
            if (!entity.getCapability(LibCapabilities.SOUL_CAPABILITY).isPresent()){
                event.addCapability(SaintChapter.key("soul_strength"), new SoulCapabilityProvider());
                SaintChapter.LOGGER.info("Mob Soul Capability attached");
            }
        }
    }
}

public interface ISoulCapability extends INBTSerializable<CompoundNBT> {
    int getSoulStrength ();
    boolean getInitialized();
}

public class SoulCapability implements ISoulCapability {
    private int soulStrength;
    private boolean initialized;

    public SoulCapability(int soulStrength, boolean isInitialized) {
        this.soulStrength = soulStrength;
        this.initialized = isInitialized;
    }

    @Override
    public boolean getInitialized() {
        return this.initialized;
    }

    @Override
    public int getSoulStrength() {
        return soulStrength;
    }


    @Override
    public CompoundNBT serializeNBT() {
        CompoundNBT compoundNBT = new CompoundNBT();
        compoundNBT.putInt("soulStrength", this.soulStrength);
        compoundNBT.putBoolean("initialized", this.initialized);
        return compoundNBT;
    }

    @Override
    public void deserializeNBT(CompoundNBT nbt) {
        this.soulStrength = nbt.getInt("soulStrength");
        this.initialized = nbt.getBoolean("initialized");
    }
}

public class SoulCapabilityProvider implements ICapabilityProvider, INBTSerializable<CompoundNBT> {
    private ISoulCapability soulCapability;

    @Nonnull
    @Override
    public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap, @Nullable Direction side) {
        return cap == LibCapabilities.SOUL_CAPABILITY ? LazyOptional.of(this::getOrCreateCapability).cast() : LazyOptional.empty();
    }

    @Nonnull
    private ISoulCapability getOrCreateCapability() {
        if (soulCapability == null) {
            this.soulCapability = new SoulCapability(888, false);
        }
        return this.soulCapability;
    }

    @Override
    public CompoundNBT serializeNBT() {
        return getOrCreateCapability().serializeNBT();
    }

    @Override
    public void deserializeNBT(CompoundNBT nbt) {
        getOrCreateCapability().deserializeNBT(nbt);
    }
}

 

I have found the answer,  use serializeNBT#getInt can get right data, Is it because the data storage in the  CapabilityProvider?