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Collection(Set,HashSet,LinkedHashSet)

Set:-Set is a child interface of collection, set is used to represent group of individual objects as a single entity where duplicates not allowed and not maintain the insertion order of elements. In case of duplicate insertion add method return false otherwise return true,here HashSet is implemented class on Set interface.
Example1:-TestSet.java
import java.util.*;
class TestSet
{
public static void main(String[]args)
{
Set s=new HashSet();
System.out.println(s);
s.add(1);
s.add(2);
s.add(3);
s.add(4);
System.out.println(s);
System.out.println("Set elements by Iterator");
Iterator itr=s.iterator();
while(itr.hasNext())
{
System.out.println(itr.next());
}
}
}
Output:-
C:\JAVATECH>javac TestSet.java
C:\JAVATECH>java TestSet
[]
[1, 2, 3, 4]
Set elements by Iterator
1
2
3
4
Example2:-TestSet.java
import java.util.*;
class TestSet
{
public static void main(String[]args)
{
Set s=new HashSet();
System.out.println(s);
s.add(4);
s.add(3);
s.add(2);
s.add(1);
System.out.println(s);
System.out.println("Set elements by Iterator");
Iterator itr=s.iterator();
while(itr.hasNext())
{
System.out.println(itr.next());
}
}
}
Output:-
C:\JAVATECH>javac TestSet.java
C:\JAVATECH>java TestSet
[]
[1, 2, 3, 4]
Set elements by Iterator
1
2
3
4
Example3:-TestSet.java
import java.util.*;
class TestSet
{
public static void main(String[]args)
{
Set s=new HashSet();
System.out.println(s);
s.add(4);
s.add(2);
s.add(1);
s.add(3);
System.out.println(s);
System.out.println("Set elements by Iterator");
Iterator itr=s.iterator();
while(itr.hasNext())
{
System.out.println(itr.next());
}
}
}
Output:-
C:\JAVATECH>javac TestSet.java
C:\JAVATECH>java TestSet
[]
[1, 2, 3, 4]
Set elements by Iterator
1
2
3
4
Example4:-TestSet.java
import java.util.*;
class TestSet
{
public static void main(String[]args)
{
Set s=new HashSet();
System.out.println(s);
s.add("Mango");
s.add("Apple");
s.add("Graps");
s.add("Orange");
System.out.println(s);
System.out.println("Set elements by Iterator");
Iterator itr=s.iterator();
while(itr.hasNext())
{
System.out.println(itr.next());
}
}
}
Output:-
C:\JAVATECH>javac TestSet.java
C:\JAVATECH>java TestSet
[]
[Apple, Graps, Mango, Orange]
Set elements by Iterator
Apple
Graps
Mango
Orange

Example5:-TestSet.java
import java.util.*;
class TestSet
{
public static void main(String[]args)
{
Set s=new HashSet();
System.out.println(s);
s.add("Mango");
s.add(1);
s.add(new Integer(2));
s.add(null);
System.out.println(s);
System.out.println("Set elements by Iterator");
Iterator itr=s.iterator();
while(itr.hasNext())
{
System.out.println(itr.next());
}
}
}
Output:-
C:\JAVATECH>javac TestSet.java
C:\JAVATECH>java TestSet
[]
[null, 1, 2, Mango]
Set elements by Iterator
null
1
2

Mango
LinkedHashSet:-LinkedHashSet is a child class of HashSet class in a HashSet class duplicate objects are not allowed and insertion order is not maintain, if we do not need duplicate object but objects comes according to insertion order than we have to use LinkedHashSet.
Example1:-TestSet.java
import java.util.*;
class TestSet
{
public static void main(String[]args)
{
LinkedHashSet s=new LinkedHashSet();
System.out.println(s);
s.add("Mango");
s.add("Apple");
s.add("Graps");
s.add("Orange");
System.out.println(s);
System.out.println("Set elements by Iterator");
Iterator itr=s.iterator();
while(itr.hasNext())
{
System.out.println(itr.next());
}
}
}
Output:-
C:\JAVATECH>javac TestSet.java
C:\JAVATECH>java TestSet
[]
[Mango, Apple, Graps, Orange]
Set elements by Iterator
Mango
Apple
Graps
Orange
Example2:-TestSet.java
import java.util.*;
class TestSet
{
public static void main(String[]args)
{
LinkedHashSet s=new LinkedHashSet();
System.out.println(s);
s.add("Mango");
s.add(1);
s.add(null);
s.add("Orange");
System.out.println(s);
System.out.println("Set elements by Iterator");
Iterator itr=s.iterator();
while(itr.hasNext())
{
System.out.println(itr.next());
}
}
}
Output:-
C:\JAVATECH>javac TestSet.java
C:\JAVATECH>java TestSet
[]
[Mango, 1, null, Orange]
Set elements by Iterator
Mango
1
null

Orange
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