Skip to main content

java treemap example

TreeMap:-TreeMap is a implemented class of map interface where elements store on the basis of key value pair and according to some sorting order of keys .

Example1:- TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new TreeMap<Object,Object>();
m.put(101,"Sumit");
m.put(104,"Sunita");
m.put(102,"Suman");
m.put(107,"Sonu");
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    :::: Sumit
102    :::: Suman
104    :::: Sunita
107    :::: Sonu
Example2:- TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new TreeMap<Object,Object>();
m.put("A","Sumit");
m.put("C","Sunita");
m.put("K","Suman");
m.put("B","Sonu");
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
A    :::: Sumit
B    :::: Sonu
C    :::: Sunita
K    :::: Suman
Example3:- TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new TreeMap<Object,Object>();
m.put(null,"Sonu");
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:- Exception in thread "main" java.lang.NullPointerException.
Example4:-TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new TreeMap<Object,Object>();
m.put(101,null);
m.put(102,null);
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    :::: null
Example5:-TestMap.java
import java.util.*;
class TestMap
{
public static void main(String[]args)
{
Map<Object,Object> m=new TreeMap<Object,Object>();
m.put(101,"Sonu");
m.put(102,"Monu");
m.put(101,"Mona");
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    :::: Mona
102    :::: Monu
Example6:-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 TreeMap<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(1033,s3);
m.put(1044,s4);
m.put(1011,s1);
m.put(1022,s2);
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
Labels:

Comments

Post a Comment

Popular posts from this blog

Inheritance-4

Example10:- class Student { Student() { System.out.println("This is super class Zero argument constructor"); } Student(String s) { System.out.println("This is super class One argument constructor"); } } class Test extends Student { Test() { super(null); System.out.println("This is sub class Zero argument constructor"); } public static void main(String[]args) { Test t=new Test(); } } Output:- C:\JAVATECH>javac Test.java C:\JAVATECH>java Test This is super class One argument constructor This is sub class Zero argument constructor Example11:- class Student { Student() { System.out.println("This is super class Zero argument constructor"); } Student(String s) { System.out.println("This is super class One argument constructor"); } } class Test extends Student { Test() { super(); super(null); System.out.println("This is su...
Post a Comment
Read more

Regarding class files

Class files:- Regarding class file or dot class file also known as byte code of class, in a java programming language we can use any number of classes in our program. After compilation all classes convert into individual   .class   file. Example:- class A { } class B { } class C { } class Student { public static void main(String[]args) { System.out.println("Well-come to my java blog"); } } We can save above program to any   classname.java   or we can use any other   name.java,   there is no compulsion for java file name. But recommended to save by that class name which having main method. I saved the above file to   Student.java   name .   Before compilation my   C:\JAVATECH   folder contain only one java file. Student.java For  compilation. C:\JAVATECH>javac  Student.java After compilation   my   C:\JAVATECH   folder contains five files, on...
Post a Comment
Read more

Inner classes

Inner Classes:- class inside class or interface called inner class or nested class. Advantage of inner classes is grouping multiple classes and interfaces into a single class. Another big advantage of inner class is that inner class can happily access all the data or variables of outer class directly. Types of Nested classes:- There are two types of nested classes static and non-static nested classes. (A)Non –static inner classes:- 1)     Member inner class 2)     Anonymous inner class 3)     Local inner class (B)Static nested class Example1:-Outer.java class Outer { class Inner { void disp() { System.out.println("Hello This is Inner class Method"); } } public static void main(String[]args) { Inner in=new Inner(); in.disp(); } } Output:- C:\JAVATECH>javac Outer.java Outer.java:12: error: non-static variable this cannot be referenced from a static context Inner in=new Inner(); ...
Post a Comment
Read more