无法使用 gson.toJson(Element) 获取 JSON 字符串，{模块 java.base 不会“打开 java.util”到模块 com.google.gson]

Question

I am developing a minecraft-forge mod that collecst data from the game and converts the whole data as a JSON string. The mod was working fine while my class had just these fields:

public class MyInfo {

    public int ID;
    public float Health;
    public double X;
    public double Y;
    public double Z;

    public MyInfo(Player play) {
        ID = play.getId();
        Health = play.getHealth();
        X = play.getX();
        Y = play.getY();
        Z = play.getZ();
    }

Player is an instance of net.minecraft.world.entity.player.Player where I can retrieve some data I want.

It was working fine and the line where I make the JSON string was not facing any issue.

Gson _Json = new GsonBuilder().setPrettyPrinting().create();
MyInfo pers = new MyInfo(player);
String Data = _Json.toJson(pers);

THE ISSUE:

As soon as I add an ArrayList field inside my MyInfo class, as I will show now:

public class MyInfo {

    public int ID;
    public float Health;
    public double X;
    public double Y;
    public double Z;
    public ArrayList<MobEffectInstance> ActivePotionEffects;

    public MyInfo(Player play) {
        ID = play.getId();
        Health = play.getHealth();
        X = play.getX();
        Y = play.getY();
        Z = play.getZ();
        ActivePotionEffects = new ArrayList<>(play.getActiveEffects()); //the method .getActiveEffects returns a Collection<MobEffectIstance>
    }

The thread encounters an exception as soon as it reaches the line where i use _Json.toJson(pers) , the exception says:

Exception in thread "Thread-6" java.lang.reflect.InaccessibleObjectException: 
Unable to make field private final java.util.concurrent.atomic.AtomicLong java.util.Random.seed accessible: module java.base does not "opens java.util" to module com.google.gson
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:178)
at java.base/java.lang.reflect.Field.setAccessible(Field.java:172)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.reflect.UnsafeReflectionAccessor.makeAccessible(UnsafeReflectionAccessor.java:44)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:159)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)        
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)        
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.CollectionTypeAdapterFactory.create(CollectionTypeAdapterFactory.java:53) 
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)        
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)        
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)        
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.CollectionTypeAdapterFactory.create(CollectionTypeAdapterFactory.java:53) 
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)        
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.createBoundField(ReflectiveTypeAdapterFactory.java:117)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:166)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:102)        
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.getAdapter(Gson.java:489)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.toJson(Gson.java:727)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.toJsonTree(Gson.java:628)
at MC-BOOTSTRAP/com.google.gson@2.8.9/com.google.gson.Gson.toJsonTree(Gson.java:607)

If I instantiate an ArrayList<Integer> in the same class where _Json is instantiated and filling it thanks to FOR loop, and then using toJson() , the problem about accessing to java.lang for Gson doesn't appear

ie:

ArrayList<Integer> numbers = new ArrayList<>();
for (int i = 0; i < 10; i++) {
       numbers.add(i);
}
Gson _Json = new GsonBuilder().setPrettyPrinting().create();
MyInfo playr = new MyInfo(player); 
String Data = _Json.toJson(numbers); //<-- not passing *playr* anymore, but *numbers*  

EDIT:

I found a workaround, it mainly works for my purpose, and is to have the type MobEffectInstance decomposed into primitive data types (ie String or Integer ) and put these values ​​inside a collection

public class MyInfo {

    public int ID;
    public float Health;
    public double X;
    public double Y;
    public double Z;
    public HashMap<String,Integer> ActivePotionEffects;

    public MyInfo(Player play) {
        ID = play.getId();
        Health = play.getHealth();
        X = play.getX();
        Y = play.getY();
        Z = play.getZ();
        ActivePotionEffects = new HashMap<>();
        ArrayList<MobEffectInstance> Temp = new ArrayList<>(play.getActiveEffects());
        for (MobEffectInstance mobEffectInstance : Temp) {
            ActivePotionEffects.put(mobEffectInstance.getDescriptionId(), mobEffectInstance.getDuration());
        }
    }

Answer 1

在初始化数组列表的地方，你有空的 <> 括号，它们应该有 MobEffectInstance 。