I've tried to use Reflection to get the "debugFPS" field like below :

int fps = 0;
try {
	Field field = mc.getClass().getDeclaredField("debugFPS");
	field.setAccessible(true);
	fps = (int) field.get(mc);
} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {
	e.printStackTrace();
}

but it only works on dev one, not working on compiled one. Anything I did not noticed?

Ok, my exception part is fixed, but after a further discover, I don't know what the "E" in the code below should be.......

@Nullable
    public static <T, E> T getPrivateValue(Class<? super E> classToAccess, E instance, String fieldName)
    {
        try
        {
            return (T) findField(classToAccess, fieldName).get(instance);
        }
        catch (UnableToFindFieldException e)
        {
            LOGGER.error(REFLECTION,"Unable to locate field {} ({}) on type {}", fieldName, remapName(INameMappingService.Domain.FIELD, fieldName), classToAccess.getName(), e);
            throw e;
        }
        catch (IllegalAccessException e)
        {
            LOGGER.error(REFLECTION,"Unable to access field {} ({}) on type {}", fieldName, remapName(INameMappingService.Domain.FIELD, fieldName), classToAccess.getName(), e);
            throw new UnableToAccessFieldException(e);
        }
    }

It says "The type of the classToAccess."

After a compiled run, it says no such field, how can I get the field I want? (note: the field calls "debugFPS")