import java.util.Arrays; import java.util.HashSet; import java.util.LinkedHashSet; import java.util.Set; import java.util.TreeSet; public class MainClass { static void fill(Set s) { s.addAll(Arrays.asList("one two three four five six seven".split(" "))); } public static void test(Set s) { System.out.println(s.getClass().getName().replaceAll("\\w+\\.", "")); fill(s); fill(s); fill(s); System.out.println(s); // No duplicates! s.addAll(s); s.add("one"); s.add("one"); s.add("one"); System.out.println(s); System.out.println("s.contains(\"one\"): " + s.contains("one")); } public static void main(String[] args) { test(new HashSet()); test(new TreeSet()); test(new LinkedHashSet()); } }
HashSet [one, two, five, four, three, seven, six] [one, two, five, four, three, seven, six] s.contains("one"): true TreeSet [five, four, one, seven, six, three, two] [five, four, one, seven, six, three, two] s.contains("one"): true LinkedHashSet [one, two, three, four, five, six, seven] [one, two, three, four, five, six, seven] s.contains("one"): true