# Things you can do with Sets : Set « Collections Data Structure « Java

Things you can do with Sets

```
// : c11:Set1.java
// Things you can do with Sets.
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.TreeSet;

public class Set1 {

static void fill(Set s) {
s.addAll(Arrays.asList("one two three four five six seven".split(" ")));
}

public static void test(Set s) {
// Strip qualifiers from class name:
System.out.println(s.getClass().getName().replaceAll("\\w+\\.", ""));
fill(s);
fill(s);
fill(s);
System.out.println(s); // No duplicates!
// Add another set to this one:
System.out.println(s);
// Look something up:
System.out.println("s.contains(\"one\"): " + s.contains("one"));
}

public static void main(String[] args) {
test(new HashSet());
test(new TreeSet());
}
} ///:~

```

### Related examples in the same category

 1 Set, HashSet and TreeSet 2 Set operations: union, intersection, difference, symmetric difference, is subset, is superset 3 Set implementation that use == instead of equals() 4 Set that compares object by identity rather than equality 5 Set union and intersection 6 Set with values iterated in insertion order. 7 Putting your own type in a Set 8 Use set 9 Another Set demo 10 Set subtraction 11 Working with HashSet and TreeSet 12 TreeSet Demo 13 Show the union and intersection of two sets 14 Demonstrate the Set interface 15 Array Set extends AbstractSet 16 Sync Test 17 Set Copy 18 Set and TreeSet 19 Tail 20 What you can do with a TreeSet 21 Remove all elements from a set 22 Copy all the elements from set2 to set1 (set1 += set2), set1 becomes the union of set1 and set2 23 Remove all the elements in set1 from set2 (set1 -= set2), set1 becomes the asymmetric difference of set1 and set2 24 Get the intersection of set1 and set2, set1 becomes the intersection of set1 and set2 25 Extend AbstractSet to Create Simple Set 26 Int Set 27 One Item Set 28 Small sets whose elements are known to be unique by construction 29 List Set implements Set 30 Converts a char array to a Set 31 Converts a string to a Set 32 Implements the Set interface, backed by a ConcurrentHashMap instance 33 An IdentitySet that uses reference-equality instead of object-equality 34 An implementation of the java.util.Stack based on an ArrayList instead of a Vector, so it is not synchronized to protect against multi-threaded access. 35 A thin wrapper around a List transforming it into a modifiable Set. 36 A thread-safe Set that manages canonical objects 37 This program uses a set to print all unique words in System.in 38 Indexed Set 39 An ObjectToSet provides a java.util.Map from arbitrary objects to objects of class java.util.Set. 40 Sorted Multi Set 41 Fixed Size Sorted Set 42 Set operations 43 A NumberedSet is a generic container of Objects where each element is identified by an integer id. 44 Set which counts the number of times a values are added to it. 45 Set which counts the number of times a values are added to it and assigns them a unique positive index. 46 Indexed Set 47 A set acts like array. 48 Implements a Bloom filter. Which, as you may not know, is a space-efficient structure for storing a set. 49 Implementation of disjoint-set data structure 50 Call it an unordered list or a multiset, this collection is defined by oxymorons