MiscTest5.java

package app1;

import app1.pkg.Other;
import java.util.List;

public class MiscTest5 {
  public static void main(String[] args) throws Exception {
    System.out.println(System.getProperty("java.version"));
    List<String> list = Other.getList();
    System.out.println("Normal: " + list.size());
    System.out.println("Reflective: " + list.getClass().getMethod("size").invoke(list));
  }
}

Other.java

package app1.pkg;

import java.util.ArrayList;
import java.util.List;

public class Other {
  static class MyList extends ArrayList<String> {
    public int size() {
      return super.size();
    }
  }

  public static List<String> getList() {
    return new MyList();
  }
}

output

$ java app1.MiscTest5
1.8.0_102
Normal: 0
Exception in thread "main" java.lang.IllegalAccessException: Class app1.MiscTest5 can not access a member of class app1.pkg.Other$MyList with modifiers "public"
	at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102)
	at java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:296)
	at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:288)
	at java.lang.reflect.Method.invoke(Method.java:491)
	at app1.MiscTest5.main(MiscTest5.java:11)