GarbageCollectors.java

import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.util.Set;

import javax.management.MBeanServer;
import javax.management.ObjectName;

/**
 * Print the Collector used in the program.
 * @author khotyn
 */
public class GarbageCollectors {

    public static void main(String[] args) throws InterruptedException, IOException {
        MBeanServer server = ManagementFactory.getPlatformMBeanServer();
        Set<ObjectName> names = server.queryNames(null, null);
        for (ObjectName name : names) {
            if (name.toString().contains("GarbageCollector")) {
                System.out.println("  " + name.getKeyProperty("name"));
            }
        }
    }
}

gc.sh

for flag in \
  -client \
  -server \
  -XX:+UseSerialGC \
  -XX:+UseParallelGC \
  -XX:+UseParNewGC \
  -XX:+UseParallelOldGC \
  -XX:+UseConcMarkSweepGC \
  -XX:+UseG1GC
do
  echo $flag
  java $flag GarbageCollectors
done

out

-client
  ConcurrentMarkSweep
  ParNew
-server
  PS MarkSweep
  PS Scavenge
-XX:+UseSerialGC
  Copy
  MarkSweepCompact
-XX:+UseParallelGC
  PS MarkSweep
  PS Scavenge
-XX:+UseParNewGC
  ParNew
  MarkSweepCompact
-XX:+UseParallelOldGC
  PS MarkSweep
  PS Scavenge
-XX:+UseConcMarkSweepGC
  ConcurrentMarkSweep
  ParNew
-XX:+UseG1GC
  G1 Old Generation
  G1 Young Generation