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[1.15] Get capibily from player as interface

KidKoderMod033109

By KidKoderMod033109
in Modder Support

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KidKoderMod033109 Creeper Killer

KidKoderMod033109

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Hi again,

I was working on my capibily and found a casting error, it read: 

Caused by: java.lang.ClassCastException: net.minecraftforge.common.util.LazyOptional cannot be cast to net.kidkoder.allergies.capability.allergies.IAllergies

so, I found the line and it reads: 

IAllergies allergies = (IAllergies) player.getCapability(AllergiesProvider.ALLERGIES_CAP);

and I don't know how to properly cast to the coreect type. The IAllergies is the inferfaced used in my capabily. If threre is a way to cast it how?

Thanks in advance,

Kid Koder

Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

ChampionAsh5357 Reality Controller

ChampionAsh5357

Posted
Posted

Do not cast from LazyOptional<IAllergies> to IAllergies. LazyOptional is quite similar to Optional found in standard java. If you want to do it your way, you should first check if the value is present in the optional (LazyOptional#isPresent) and then get the value (LazyOptional#getValue). You can also use (LazyOptional#ifPresent) instead.

KidKoderMod033109 Creeper Killer

KidKoderMod033109

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Ok, great! But I saw on the file that I could use Capability.orEmpty(Capability, LazyOptional) to cast it. Or am understading it wrong?

Also, LazyOptional#getValue does not seem to exist? I need help finding the method. Also, would this be what you meant?

 
 
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Thanks once again,

Kid Koder

Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

ChampionAsh5357 Reality Controller

ChampionAsh5357

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Posted (edited)

Apologies, I just glanced at the code. LazyOptional#getValue is private. You need to use either orElse, orElseGet, orElseThrow to get the desired result. And yes, something like that would work. Either one will work since you already check if its present. Just make sure you put a valid instance as the parameter. I usually prefer LazyOptional#orElseThrow because I don't want to a null default if it fails.

Edited by ChampionAsh5357
ChampionAsh5357 Reality Controller

ChampionAsh5357

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Posted

The first method needs a defaulted instance, the second method needs a defaulted instance passed through a Supplier, and the third method uses a supplier of an exception. Suppliers can be easily made using: 

() -> value

 

As for how to look for code, in Eclipse I just ctrl + left click and it opens the source for me. If it doesn't exist, I look for a javadoc on the internet.

KidKoderMod033109 Creeper Killer

KidKoderMod033109

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  On 4/16/2020 at 12:27 AM, ChampionAsh5357 said: 
IAllergies allergies = player.getCapability(AllergiesProvider.ALLERGIES_CAP).orElseThrow(() -> new RuntimeException("This capability does not exist"));

 

There's a button called TeleType and it looks like tt.

Expand  

??. I'm using IntelliJ IDEA, where could I find this.

Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

KidKoderMod033109 Creeper Killer

KidKoderMod033109

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Great would this code work?

 
 
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Thank you

Kid Koder

Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

Draco18s Reality Controller

Draco18s

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Or you can use ifPresent. 

player.getCapability(AllergiesProvider.ALLERGIES_CAP).ifPresent(allergies -> {
	//your code here
});

 

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

Alpvax Diamond Finder

Alpvax

Posted
Posted (edited)

You can simplify it, you are checking whether it is present twice: 

//Either
IAllergies allergies = allergiesLazyOptional.orElseGet(CapabilityAllergies::new);
//Or
IAllergies allergies = allergiesLazyOptional.orElse(new CapabilityAllergies());

The whole point of the "orElse" methods is to do something else if it is not present.

 

`CapabilityAllergies::new` is the same as `() -> new CapabilityAllergies()`: A method which takes no arguments and returns an instance of CapabilityAllergies.

Edited by Alpvax
Fixed error in code
KidKoderMod033109 Creeper Killer

KidKoderMod033109

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Posted (edited)
  On 4/16/2020 at 12:37 PM, Alpvax said:

You can simplify it, you are checking whether it is present twice: 

IAllergies allergies = allergiesLazyOptional.orElse(CapabilityAllergies::new);

The whole point of the "orElse" methods is to do something else if it is not present.

 

`CapabilityAllergies::new` is the same as `() -> new CapabilityAllergies()`: A method which takes no arguments and returns an instance of CapabilityAllergies.

Expand  

I used this line, but for CapabilityAllergies::new  IntelliJ said that IAllergies was a functional interface.

Edited by KidKoderMod033109

Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

Alpvax Diamond Finder

Alpvax

Posted
Posted (edited)
  On 4/16/2020 at 4:15 PM, KidKoderMod033109 said:

I used this line, but for CapabilityAllergies::new  IntelliJ said that IAllergies was a functional interface.

Expand  

My mistake, I didn't have access to the code at the time.

It should be either .orElseGet(CapabilityAllergies::new) or .orElse(new CapabilityAllergies()).

The difference is that the first option will not create a new instance unless it is required, whereas the second will regardless. (Which you use will probably only result in a minor performance difference).

Edited by Alpvax
More information
KidKoderMod033109 Creeper Killer

KidKoderMod033109

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I got a java.lang.NullPointerException for this class:

 
 
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Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

Alpvax Diamond Finder

Alpvax

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  On 4/16/2020 at 4:30 PM, diesieben07 said:

If the capability isnt attached here it is most likely an error. orElseThrow should be used.

Expand  

Probably true, but as the initial code created a new capability if there wasn't an existing one, I repeated that functionality.

KidKoderMod033109 Creeper Killer

KidKoderMod033109

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Here is the log:

 
 
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Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

Draco18s Reality Controller

Draco18s

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  Quote

Stacktrace:

    at net.kidkoder.allergies.system.Events.newPlayerJoinWorld(Events.java:47)

Expand  
  On 4/16/2020 at 5:03 PM, diesieben07 said:

And line 47 is...?

Expand  

Line 47 of your code is...?

Apparently I'm a complete and utter jerk and come to this forum just like to make fun of people, be confrontational, and make your personal life miserable.  If you think this is the case, JUST REPORT ME.  Otherwise you're just going to get reported when you reply to my posts and point it out, because odds are, I was trying to be nice.

 

Exception: If you do not understand Java, I WILL NOT HELP YOU and your thread will get locked.

 

DO NOT PM ME WITH PROBLEMS. No help will be given.

KidKoderMod033109 Creeper Killer

KidKoderMod033109

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  On 4/17/2020 at 3:23 PM, diesieben07 said:

getAllergens returned null.

And that orElse is still nonsensicle.

Expand  

Ok, ya true, so how can I fix that?

Also, that line I sent a minute ago was line 48, this is line 47: 

            PlayerAllergies playerAllergies = player.getCapability(AllergiesProvider.ALLERGIES_CAP).orElse(new CapabilityAllergies()).getAllergens();

 

Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

KidKoderMod033109 Creeper Killer

KidKoderMod033109

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Posted
  On 4/17/2020 at 3:40 PM, diesieben07 said:

This is why you post your code as a Git repo!

 

Expand  

I did. It is located here: https://github.com/KidKoder09923/Allergies-Mod

  On 4/17/2020 at 3:40 PM, diesieben07 said:

If that is line 47 then that means that your ICapabilityProvider returned a LazyOptional with a null inside (that should log a warning "Supplier should not return null value").

Expand  

Also, back the orginial question, how would I convert the LazyOptional to an IAllergies. I still geting a java.lang.NullPointerExeption

Website: http://kidkoder.net

GitHub: https://github.com/Uncodeable864

Animefan8888 Reality Controller

Animefan8888

Posted
Posted (edited)
  On 4/17/2020 at 4:06 PM, KidKoderMod033109 said:

I did. It is located here: https://github.com/KidKoder09923/Allergies-Mod

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You never linked it how were we supposed to know or have access to it.
 

  Quote

@SubscribeEvent

public void attachCapability(AttachCapabilitiesEvent event) {

event.addCapability(ALLERGIES_LOC, new AllergiesProvider());

}

Expand  

You need to specify what you are attaching it to IE AttachCapabilitiesEvent<Entity>

then to only attach it to player do if (event.getObject() instanceof PlayerEntity)

then add the Capability.

  Quote

@Nonnull

@Override

public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap, @Nullable Direction side) {

return null;

}

@Nonnull

@Override

public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap) {

return null;

}

Expand  

Here's your NullPointerException an issue...

 

Did you forget to update your git repo?

Edited by Animefan8888

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I will be posting 1.15.2 modding tutorials on this channel. If you want to be notified of it do the normal YouTube stuff like subscribing, ect.

Forge and vanilla BlockState generator.

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