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LinkedHashMap(Collection)

LinkedHashMap:-LinkedHashMap is child class of HashMap class where object store in the form of key value pair and maintain insertion order.
Example1:- TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map m=new LinkedHashMap();
m.put(101,"Java");
m.put(102,"Cpp");
m.put(103,"C#");
m.put(104,"C");
m.put("Amit",101);
m.put("Neha",102);
System.out.println(m);
}
}
Output:-
{101=Java, 102=Cpp, 103=C#, 104=C, Amit=101, Neha=102}
Example2:-TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new LinkedHashMap<Object,Object>();
m.put(101,"Java");
m.put(102,"Cpp");
m.put(103,"C#");
m.put(104,"C");
m.put("Amit",101);
m.put("Neha",102);
Set s=m.entrySet();
Iterator itr=s.iterator();
System.out.println("Key   :::::::::Value");
while(itr.hasNext())
{
Map.Entry me=(Map.Entry)itr.next();
System.out.println(me.getKey()+"    :::: "+me.getValue());
}
}
}
Output:-
Key   :::::::::Value
101    :::: Java
102    :::: Cpp
103    :::: C#
104    :::: C
Amit    :::: 101
Neha    :::: 102
Example3:- TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new LinkedHashMap<Object,Object>();
m.put(101,"Java");
m.put(102,"java");
m.put(102,"C#");
m.put(104,null);
m.put("Amit",101);
m.put("Neha",102);
Set s=m.entrySet();
Iterator itr=s.iterator();
System.out.println("Key   :::::::::Value");
while(itr.hasNext())
{
Map.Entry me=(Map.Entry)itr.next();
System.out.println(me.getKey()+"    :::: "+me.getValue());
}
}
}
Output:-
Key   :::::::::Value
101    :::: Java
102    :::: C#
104    :::: null
Amit    :::: 101
Neha    :::: 102
Example4:- TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new LinkedHashMap<Object,Object>();
m.put(101,null);
m.put(102,"java");
m.put(102,"C#");
m.put(104,null);
m.put(null,101);
m.put(null,102);
Set s=m.entrySet();
Iterator itr=s.iterator();
System.out.println("Key   :::::::::Value");
while(itr.hasNext())
{
Map.Entry me=(Map.Entry)itr.next();
System.out.println(me.getKey()+"    :::: "+me.getValue());
}
}
}
Output:-
Key   :::::::::Value
101    :::: null
102    :::: C#
104    :::: null
null    :::: 102
Example5:-TestMap.java
import java.util.*;
class Student
{
int rollno;
String name,course;
Student(int rollno,String name,String course)
{
this.rollno=rollno;
this.name=name;
this.course=course;
}
}
class TestMap
{
public static void main(String[]args)
{
Map<Object,Student> m=new LinkedHashMap<Object,Student>();
Student s1=new Student(101,"Neha","M.Tech");
Student s2=new Student(102,"Nisha","B.Tech");
Student s3=new Student(103,"Nehal","M.C.A");
Student s4=new Student(104,"Namita","MSC");
m.put(1011,s1);
m.put(1022,s2);
m.put(1033,s3);
m.put(1044,s4);
Set ss=m.entrySet();
Iterator itr=ss.iterator();
System.out.println("Key   :::::::::Value");
while(itr.hasNext())
{
Map.Entry me=(Map.Entry)itr.next();
Student s=(Student)me.getValue();
System.out.println(me.getKey()+"    :::: "+s.rollno+"  "+s.name+"  "+s.course);
}
}
}
Output:-
Key   :::::::::Value
1011    :::: 101  Neha  M.Tech
1022    :::: 102  Nisha  B.Tech
1033    :::: 103  Nehal  M.C.A

1044    :::: 104  Namita  MSC
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