class obj {
  void afunction(Object o) {
    // some function that 
    // requires an object
  }
}

// . . . 

obj.afunction(
  new {
    public void object_func_1(void) { 
      // some code here
    }
    public void object_func_2(void) {
      // more code here
    }
  } // end of nested class
);