Android: changing private static final field using java reflection

Question

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?

You...can't change the _modifiers on a class field_ at _runtime._ — Louis Wasserman, Jun 25 '12 at 08:26
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, Jun 27 '12 at 20:28

score 10 · Accepted Answer · edited Jun 11 '18 at 21:24

10

This works for non-static fields.

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

edited Jun 11 '18 at 21:24

Andi

457
3
19

answered Jun 27 '12 at 20:10

jas7

2,893
6
23
36

1

This worked. But why? Does ART remove the final modifier or does it simple allow to access it anyway? – Yoraco Gonzales Feb 28 '16 at 17:09
This works, because the first object in the `field.set(...)` function is the object to modify NOT the field – prom85 Mar 16 '16 at 09:08
data is not static in this case? – David Williams Aug 09 '17 at 01:36

Android: changing private static final field using java reflection

1 Answers1

Linked