Java tutorial
import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; public class Main { public static void main(String[] args) { Collection<String> c = Collections.synchronizedCollection(new ArrayList<String>()); List<String> list = Collections.synchronizedList(new ArrayList<String>()); Set<String> s = Collections.synchronizedSet(new HashSet<String>()); Map<String, String> m = Collections.synchronizedMap(new HashMap<String, String>()); } }