Exception in thread "main" java.lang.IllegalArgumentException
        at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(Unknown Source)
        at sun.reflect.UnsafeObjectFieldAccessorImpl.get(Unknown Source)
        at java.lang.reflect.Field.get(Unknown Source)
        at Test_code.field_function(Test_code.java:150)
        at Test_code.main(Test_code.java:111)