HashSet element adding

In this chapter you will learn:

1. How to add elements to a HashSet

Add element to hash set

boolean add(E e) Adds the specified element to this set if it is not already present.

import java.util.HashSet;
/*from j a va 2  s  .c  o  m*/
public class Main{
    public static void main(String args[]) {
        HashSet<String> hs = new HashSet<String>();
        hs.add("java2s.com");
        hs.add("java2s.com");
        hs.add("A");
        hs.add("D");
        hs.add("E");
        hs.add("C");
        hs.add("j a v a2s.com");

        System.out.println(hs);
    }
}

The output:

In the code above we adds java2s.com twice into the set but the result only has one java2s.com since set would not allow duplicate elements.

Next chapter...

What you will learn in the next chapter:

1. How to remove all elements from a HashSet
2. How to remove an element from hash set

List interface

List add/insert elements

List clear/remove elements

List search

List element get and set

List and its Iterator

List size, empty

List conversion, to array

List to sublist

List comparison

ArrayList

ArrayList Creation

ArrayList add/insert

ArrayList get/set element

ArrayList clear/remove

ArrayList search

ArrayList copy and shallow copy

ArrayList size, trim to size and capacity

ArrayList to array

LinkedList class

LinkedList creation

LinkedList add/insert elements

LinkedList get elements

LinkedList search

LinkeList replace/set elements

LinkedList remove element

LinkedList copy

LinkedList iterator

LinkedList peek element

LinkedList pop/push element

LinkedList conversion

Map interface

Map element adding

Map.Entry class

Map key

Map value

Map key/value search

Map delete/remove

Map comparison

HashMap Class

HashMap search

HashMap clone

TreeMap

TreeMap key

TreeMap head sub map

TreeMap tail sub map

TreeMap sub map

NavigableMap

NavigableMap key

NavigableMap key-value pair

LinkedHashMap Class

IdentityHashMap

SortedMap

HashSet

HashSet element adding

HashSet element removing and clearing

HashSet clone

HashSet iterator

HashSet properties

TreeSet

TreeSet elements adding

TreeSet subSet

NavigableSet

LinkedHashSet

Iterator

ListIterator

List filling

List reversing

List rotating and shuffling

List sorting

List element swap

List element replacing

List copy

List binary search

Collection unmodifiable

Collection synchronized

Collection singleton

Collection max/min value

Empty Collections

Comparator

Comparable

Enumeration

EnumSet

EnumMap Class

PriorityQueue