Calling Calendar class functions produces GC_CONCURRENT messages

Question

I am writing a little calendar app for Android and I need some functions the Calendar class contains (for example: calculate first day of month, current day of month, day of next month, year of a specific Unix timestamp and so on)

These functions are called frequently and they trigger GC_Concurrent pretty often which causes my app to lag.

This is the way I access the calendar functions:

private static Calendar cal;

public static int getDayOfMonth(long sec) {
    if (cal == null)
        cal = Calendar.getInstance(TimeZone.getDefault());

    //cal.clear();
    cal.setTimeInMillis(sec * 1000L);
    return cal.get(Calendar.DAY_OF_MONTH);
}

Is there a better way to access the functions without producing so much garbage or a better way to calculate the things I need?

Answer 1

First question: Have you profiled the code? How certain are you that this is the problem? If you have profiled and you are certain...

---

Have you tried using Joda Time or Joda Time Android ?

Java's default support for dates and times is really terrible, generally speaking.

You can do the same code using Joda time by doing:

public static int getDayOfMonth(long sec) {
  DateTime time = new DateTime(sec * 1000L);
  return time.getDayOfMonth();
}

Answer 2

You can't stop stop garbage collection, it is a daemon thread.

It's meant to improve performance; if it's slowing your program, than there likely is a inefficient use of objects/other design flaw causing the garbage collector to have redundant tasks.

I don't want to repeat what you probably already know, but you should look @ this post, it should prove useful.

Android CalendarView slowing down layout

-Eric