How to get Private Field? [Java 8]

I was reading https://www.spigotmc.org/threads/tutorial-creating-custom-entities-with-pathfindergoals.18519/ when I came across this line:

((Map)getPrivateField("c", net.minecraft.server.v1_7_R4.EntityTypes.class, null)).put(name, clazz);

I'm using Java's jdk1.8.0_60 as well as spigot v1_9_R2 As well as craftbukkit 1.9.4

How do I get a Private Field that does the same thing?

BTW, I changed v1_7_r4 to V1_9_R2

 

Here is a great answer. http://stackoverflow.com/a/1555680/3830983

 

How do I do this multiple times [3] in one class without getting Unhandled exception type NoSuchFieldException and Unhandled exception type IllegalAccessException?

It works until I attempt to use it the third time;

Eclipse higlights (per line)

Code:

net.minecraft.server.v1_9_R2.EntityTypes.class.getDeclaredField("strD"); //or strF or strC
Object valueD = fieldD.get(D); // Or Object valueC = fieldC.get(C); or Object valueF = fieldF.get(F);

Code:
package io.github.rookietec9.EnderPlugin.Entities;

import java.lang.reflect.Field;
import java.util.Map;

import org.bukkit.Location;
import org.bukkit.World;

import io.github.rookietec9.EnderPlugin.Entities.Others.OtherC;
import io.github.rookietec9.EnderPlugin.Entities.Others.OtherD;
import io.github.rookietec9.EnderPlugin.Entities.Others.OtherF;
import net.minecraft.server.v1_9_R2.Entity;
import net.minecraft.server.v1_9_R2.EntityTypes;
class Others {

    class OtherC
{
    public void setStrC(String valueC)
    {
    }
}

class OtherD
{
    public void setStrD(String valueD)
    {
    }
}

class OtherF
{
    public void setStrF(String valueF)
    {
    }
}
class Other
{
    public void setStr(String value)
    {
    }
}

}

public enum CustomBase {

    // NAME("Entity name", Entity ID, yourcustomclass.class)

    CUSTOM_SKELETON("Skeleton", 54, CustomSkeleton.class); // You can add as
                                                            // many as you want.

    private CustomBase(String name, int id, Class<? extends Entity> custom) {
        addToMaps(custom, name, id);
    }

    public static void spawnEntity(Entity entity, Location loc) {
        Location Loc = new Location((World) entity.getWorld(), loc.getX(),loc.getY(), loc.getZ(), loc.getYaw(), loc.getPitch());
        spawnEntity(entity, Loc);
    }

    @SuppressWarnings({ "rawtypes", "unchecked"})
    private static void addToMaps(Class clazz, String name, int id) {
        // Remove the lines with // in front of them if you want to override
        // default entities (You'd have to remove the default entity from the
        // map first though).
            //START C
                // /*
                Other C = new OtherC();
                C.setStrC("c");
                Field fieldC =  net.minecraft.server.v1_9_R2.EntityTypes.class.getDeclaredField("StrC");
                fieldC.setAccessible(true);
                Object valueC = fieldC.get(C);
                // */
            //END C
            //START D
                // /*
                Other D = new OtherF();
                D.setStrF("d");
                Field fieldD =  net.minecraft.server.v1_9_R2.EntityTypes.class.getDeclaredField("strD");
                fieldD.setAccessible(true);
                Object valueD = fieldD.get(D);
                // */
            //END D
            //START F
           
                OtherF F = new OtherF();
                F.setStrF("f");
                Field fieldF =  net.minecraft.server.v1_9_R2.EntityTypes.class.getDeclaredField("strF");
                fieldF.setAccessible(true);
                Object valueF = fieldF.get(F);
                // */
            //END F
        ((Map) valueC).put(name, clazz);
        ((Map) valueD).put(clazz, name);
        // ((Map)getPrivateField("e",
        // net.minecraft.server.v1_7_R4.EntityTypes.class,
        // null)).put(Integer.valueOf(id), clazz);
        // ((Map) valueF).put(clazz, Integer.valueOf(id));
        // ((Map)getPrivateField("g",
        // net.minecraft.server.v1_7_R4.EntityTypes.class, null)).put(name,
        // Integer.valueOf(id));
    }

    }