Android: changing private static final field using java reflection

19
votes

Change private static final field using Java reflection

I followed the instructions in the link above to change a private static final field using java reflection. I have an object named "data." Inside "data," there is a private static final variable named "type." I want to set "type" to be null. Here is my code. 

Field field = data.getClass().getDeclaredField("type");
field.setAccessible(true);
Field modifiersField = Field.class.getDeclaredField("modifiers");
modifiersField.setAccessible(true);
modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
field.set(data, null);

I tried doing this on Java 1.7 with similar code and it worked. But running this code on Android produces the following error: java.lang.NoSuchFieldException: modifiers

I guess "modifiers" is not a field in the Field class on Android.

How do I fix this?

1
javaandroidreflection
You...can't change the modifiers on a class field at runtime. – Louis Wasserman
I can according to that link. – jas7
Do remember that the Java compiler can inline values of primitive static final fields. Doing this sort of reflection magic could lead to bizarre behaviour. – millimoose

1 Answers

10
votes

This works for non-static fields. 

Field field = data.getClass().getDeclaredField("type");
field.setAccessible(true);
field.set(data, null);