JAVA
Java HashSet class
Java HashSet class is used to create a collection that uses a
hash table for storage. It inherits the AbstractSet class and implements Set
interface.
The important points about Java HashSet class are:
·
HashSet
stores the elements by using a mechanism called hashing.
·
HashSet
contains unique elements only.
Methods of Java HashSet class:
|
Method |
Description |
|
void clear() |
It is used to remove all of the elements from
this set. |
|
boolean contains(Object o) |
It is used to return true if this set
contains the specified element. |
|
boolean add(Object o) |
It is used to adds the specified element to
this set if it is not already present. |
|
boolean isEmpty() |
It is used to return true if this set
contains no elements. |
|
boolean remove(Object o) |
It is used to remove the specified element
from this set if it is present. |
HashSet example program
public class HashSet{
public static void main(String args[]){
HashSet set=new HashSet();
set.add("Sindhu");
set.add("Deepthi");
set.add("Chandrakala");
set.add("Sai
Charan");
set.add("Maithili");
set.add("Deepya");
set.add("Jeeshitha");
set.add("Sunitha");
Iterator itr=set.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
}
}}
OUTPUT
Sai Charan
Maithili
Sunitha
Deepthi
Chandrakala
Deepya
Jeeshitha
Java LinkedHashSet
class
Java LinkedHashSet class is a Hash table and Linked list
implementation of the set interface. It inherits HashSet class and implements
Set interface.
The important points about Java LinkedHashSet class are:
Contains unique elements only like HashSet.
Provides all optional set operations, and permits null
elements.
Maintains insertion order.
Methods of Java LinkedHashSet class:
|
Method |
Description |
|
void clear() |
It is used to remove all of the elements from
this set. |
|
boolean contains(Object o) |
It is used to return true if this set
contains the specified element. |
|
boolean add(Object o) |
It is used to adds the specified element to
this set if it is not already present. |
LinkedeHashset Example program
public class Del{
public static void main(String args[]){
LinkedHashSet set=new LinkedHashSet();
set.add("Sindhu");
set.add("Deepthi");
set.add("Chandrakala");
set.add("Sai
Charan");
set.add("Maithili");
set.add("Deepya");
set.add("Jeeshitha");
set.add("Sunitha");
Iterator itr=set.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
}
}}
OUTPUT:
Sindhu
Deepthi
Chandrakala
Sai Charan
Maithili
Deepya
Jeeshitha
Sunitha
Java TreeSet class
Java TreeSet class implements the Set interface that uses a
tree for storage. It inherits AbstractSet class and implements NavigableSet
interface. The objects of TreeSet class are stored in ascending order.
The important points about Java TreeSet class are:
·
Contains
unique elements only like HashSet.
·
Access
and retrieval times are quiet fast.
·
Maintains
ascending order.
Methods of Java TreeSet class
|
Method |
Description |
|
boolean addAll(Collection c) |
It is used to add all of the elements in the
specified collection to this set. |
|
boolean contains(Object o) |
It is used to return true if this set
contains the specified element. |
TreeSet Example program
public class Del{
public static void main(String args[]){
TreeSet set=new TreeSet();
set.add("Sindhu");
set.add("Deepthi");
set.add("Chandrakala");
set.add("Sai
Charan");
set.add("Maithili");
set.add("Deepya");
set.add("Jeeshitha");
set.add("Sunitha");
Iterator itr=set.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
}
}}
OUTPUT
Chandrakala Deepthi Deepya Jeeshitha Maithili Sai Charan Sindhu Sunitha