Help with passing values to methods

Question

  GregorianCalendar baseTime = new GregorianCalendar();
  long baseSystemTime = System.currentTimeMillis();
  // After some iterations I want to update the
  // calendar to reflect the current time.
  // I do not want to go through instantiating a new calendar
  baseTime = updateTimestamp(baseTime,baseSystemTime);
  private static GregorianCalendar updateTimestamp(GregorianCalendar GC, long lastTime){
    // This gets the difference between the last time check and now.
    // It then adds that difference to the calendar and returns the updated
    // calendar.
    int msDifference =
      new Long(System.currentTimeMillis() - lastTime).intValue();
    GC.add(GregorianCalendar.MILLISECOND,msDifference);
    lastTime = new Long(System.currentTimeMillis()).longValue();
    return GC;
  }The problem is that the lastTime variable that it passed gets updated to the current MS value. But, the original baseSystemTime never changes.
I thought that if you pass something to a method and it gets altered in the method the original object is updated. Am I wrong?

Answer 1

So objects are passed by reference but primitives are
passed by value?Simply speaking: Yes.
Strictly speaking: No. Every parameter is passed by value because Object obj IS a reference. So when you do call(myObject), you are passing the value of the reference of the object (the adress of the object).