diff --git a/Area&CircumfrenceofCircle b/Area&CircumfrenceofCircle
new file mode 100644
index 0000000..2a96580
--- /dev/null
+++ b/Area&CircumfrenceofCircle
@@ -0,0 +1,19 @@
+import java.util.Scanner;
+class CircleDemo
+{
+   static Scanner sc = new Scanner(System.in);
+   public static void main(String args[])
+   {
+      System.out.print("Enter the radius: ");
+      /*We are storing the entered radius in double
+       * because a user can enter radius in decimals
+       */
+      double radius = sc.nextDouble();
+      //Area = PI*radius*radius
+      double area = Math.PI * (radius * radius);
+      System.out.println("The area of circle is: " + area);
+      //Circumference = 2*PI*radius
+      double circumference= Math.PI * 2*radius;
+      System.out.println( "The circumference of the circle is:"+circumference) ;
+   }
+}
diff --git a/CheckPrimeNumber b/CheckPrimeNumber
new file mode 100644
index 0000000..f7f0b9e
--- /dev/null
+++ b/CheckPrimeNumber
@@ -0,0 +1,19 @@
+public class PrimeExample{    
+ public static void main(String args[]){    
+  int i,m=0,flag=0;      
+  int n=3;//it is the number to be checked    
+  m=n/2;      
+  if(n==0||n==1){  
+   System.out.println(n+" is not prime number");      
+  }else{  
+   for(i=2;i<=m;i++){      
+    if(n%i==0){      
+     System.out.println(n+" is not prime number");      
+     flag=1;      
+     break;      
+    }      
+   }      
+   if(flag==0)  { System.out.println(n+" is prime number"); }  
+  }//end of else  
+}    
+}   
diff --git a/Factorial b/Factorial
new file mode 100644
index 0000000..6b6ee15
--- /dev/null
+++ b/Factorial
@@ -0,0 +1,13 @@
+//https://www.facebook.com/srishti.agrawal.714/posts/162113345582696
+//Subscribed by Srishti Agrawal
+public class Factorial
+{
+	public static void main(String[] args)
+	{
+		int n=Integer.parseInt(args[0]);
+		int f=1;
+		for(int i=1;i<=n;i++)
+			f*=i;
+		System.out.println("Factorial is "+ f);
+	}
+}
diff --git a/FactorialProgram b/FactorialProgram
new file mode 100644
index 0000000..335fbca
--- /dev/null
+++ b/FactorialProgram
@@ -0,0 +1,10 @@
+class FactorialExample{  
+ public static void main(String args[]){  
+  int i,fact=1;  
+  int number=5;//It is the number to calculate factorial    
+  for(i=1;i<=number;i++){    
+      fact=fact*i;    
+  }    
+  System.out.println("Factorial of "+number+" is: "+fact);    
+ }  
+}  
diff --git a/Fibonacci b/Fibonacci
new file mode 100644
index 0000000..52aa8eb
--- /dev/null
+++ b/Fibonacci
@@ -0,0 +1,19 @@
+public class FibonacciSeries {
+
+	public static void main(String[] args) {
+		printFibonacciSeries(10);
+	}
+
+	public static void printFibonacciSeries(int count) {
+		int a = 0;
+		int b = 1;
+		int c = 1;
+		for (int i = 1; i <= count; i++) {
+			System.out.print(a + ", ");
+			a = b;
+			b = c;
+			c = a + b;
+		}
+
+	}
+}
diff --git a/Fibonacci Series b/Fibonacci Series
new file mode 100644
index 0000000..e0f0779
--- /dev/null
+++ b/Fibonacci Series	
@@ -0,0 +1,17 @@
+public class Fibonacci {
+
+    public static void main(String[] args) {
+
+        int n = 10, t1 = 0, t2 = 1;
+        System.out.print("First " + n + " terms: ");
+
+        for (int i = 1; i <= n; ++i)
+        {
+            System.out.print(t1 + " + ");
+
+            int sum = t1 + t2;
+            t1 = t2;
+            t2 = sum;
+        }
+    }
+}
diff --git a/HelloWorld b/HelloWorld
new file mode 100644
index 0000000..e1a0fdb
--- /dev/null
+++ b/HelloWorld
@@ -0,0 +1,5 @@
+class HelloWorld {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!"); 
+    }
+}
diff --git a/MyHelloWorld b/MyHelloWorld
new file mode 100644
index 0000000..e1a0fdb
--- /dev/null
+++ b/MyHelloWorld
@@ -0,0 +1,5 @@
+class HelloWorld {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!"); 
+    }
+}
diff --git a/Palindrome b/Palindrome
new file mode 100644
index 0000000..00f167d
--- /dev/null
+++ b/Palindrome
@@ -0,0 +1,21 @@
+//https://www.facebook.com/srishti.agrawal.714/posts/162113345582696
+//Subscribed by Code House
+import java.util.Scanner; 
+class Palindrome {   
+ public static void main(String args[]) {  
+ Scanner input=new Scanner(System.in);
+  int rem,sum=0,rev;     
+  int n=input.nextInt();//It is the number variable to be checked for palindrome   
+  
+  rev=n;     
+  while(n>0) {     
+   rem=n%10;  //getting remainder   
+   sum=(sum*10)+rem;     
+   n=n/10;     
+  }     
+  if(rev==sum)     
+   System.out.println("It is a palindrome number ");     
+  else     
+   System.out.println("It is not a palindrome number");     
+}  
+}  
diff --git a/Postordertraversal.java b/Postordertraversal.java
new file mode 100644
index 0000000..2ecdd71
--- /dev/null
+++ b/Postordertraversal.java
@@ -0,0 +1,54 @@
+# https://www.facebook.com/dikshit.kaushal.564/posts/103324861581146
+# Subscribed By Dikshit Kaushal
+
+class Node {
+  int item;
+  Node left, right;
+
+  public Node(int key) {
+  item = key;
+  left = right = null;
+  }
+}
+
+class Tree {
+  // Root of Binary Tree
+  Node root;
+
+  Tree() {
+  root = null;
+  }
+
+  void postorder(Node node) {
+    if (node == null)
+      return;
+
+    // traverse the left child
+    postorder(node.left);
+
+    // traverse the right child
+    postorder(node.right);
+
+    // traverse the root node
+    System.out.print(node.item + "->");
+  }
+
+  public static void main(String[] args) {
+
+    // create an object of Tree
+    Tree tree = new Tree();
+
+    // create nodes of the tree
+    tree.root = new Node(1);
+    tree.root.left = new Node(12);
+    tree.root.right = new Node(9);
+
+    // child nodes of left child
+    tree.root.left.left = new Node(5);
+    tree.root.left.right = new Node(6);
+
+    // postorder tree traversal
+    System.out.println("Postorder traversal");
+    tree.postorder(tree.root);
+  }
+}
diff --git a/Reverse b/Reverse
new file mode 100644
index 0000000..bbaaa75
--- /dev/null
+++ b/Reverse
@@ -0,0 +1,21 @@
+public class JavaReverseString {
+
+	public static void main(String[] args) {
+		System.out.println(reverseString("abc"));
+		System.out.println(reverseString("123!@#098*"));
+	}
+
+	public static String reverseString(String in) {
+		if (in == null)
+			return null;
+		StringBuilder out = new StringBuilder();
+
+		int length = in.length();
+
+		for (int i = length - 1; i >= 0; i--) {
+			out.append(in.charAt(i));
+		}
+
+		return out.toString();
+	}
+}
diff --git a/arpit tripathi.md b/arpit tripathi.md
new file mode 100644
index 0000000..11b2295
--- /dev/null
+++ b/arpit tripathi.md	
@@ -0,0 +1,22 @@
+public class Main {
+
+    public static void main(String[] args) {
+
+        int num = 29;
+        boolean flag = false;
+        for(int i = 2; i <= num/2; ++i)
+        {
+            // condition for nonprime number
+            if(num % i == 0)
+            {
+                flag = true;
+                break;
+            }
+        }
+
+        if (!flag)
+            System.out.println(num + " is a prime number.");
+        else
+            System.out.println(num + " is not a prime number.");
+    }
+}
diff --git a/arpit.tripathi.md b/arpit.tripathi.md
new file mode 100644
index 0000000..4038bfd
--- /dev/null
+++ b/arpit.tripathi.md
@@ -0,0 +1,25 @@
+public class Test {
+
+   public static void main(String args[]) {
+      // char grade = args[0].charAt(0);
+      char grade = 'C';
+
+      switch(grade) {
+         case 'A' :
+            System.out.println("Excellent!"); 
+            break;
+         case 'B' :
+         case 'C' :
+            System.out.println("Well done");
+            break;
+         case 'D' :
+            System.out.println("You passed");
+         case 'F' :
+            System.out.println("Better try again");
+            break;
+         default :
+            System.out.println("Invalid grade");
+      }
+      System.out.println("Your grade is " + grade);
+   }
+}
diff --git a/arpittripathi.md b/arpittripathi.md
new file mode 100644
index 0000000..6079da2
--- /dev/null
+++ b/arpittripathi.md
@@ -0,0 +1,22 @@
+package MyPackage;
+ 
+public class Armstrong {
+    public static void main(String[] args) {
+        int number = 9474, originalNumber, remainder, result = 0, n = 0;
+        originalNumber = number;
+        for (;originalNumber != 0; originalNumber /= 10)
+        {
+            n++;
+        }
+        originalNumber = number;
+        for (;originalNumber != 0; originalNumber /= 10)
+        {
+            remainder = originalNumber % 10;
+            result += Math.pow(remainder, n);
+        }
+        if(result == number)
+            System.out.println(number + " is an Armstrong number.");
+        else
+            System.out.println(number + " is not an Armstrong number.");
+    }
+}
diff --git a/complex_number.java b/complex_number.java
new file mode 100644
index 0000000..a4391fd
--- /dev/null
+++ b/complex_number.java
@@ -0,0 +1,31 @@
+#https://www.facebook.com/shruti.buchha.7/posts/3341900509242443
+#subscribed by shruti buchha
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+public class ComplexNumber{
+   
+   double real, img;
+	
+   ComplexNumber(double r, double i){
+	this.real = r;
+	this.img = i;
+   }
+	
+   public static ComplexNumber sum(ComplexNumber c1, ComplexNumber c2)
+   {
+	
+        ComplexNumber temp = new ComplexNumber(0, 0);
+
+        temp.real = c1.real + c2.real;
+        temp.img = c1.img + c2.img;
+
+        return temp;
+    }
+    public static void main(String args[]) {
+	ComplexNumber c1 = new ComplexNumber(5.5, 4);
+	ComplexNumber c2 = new ComplexNumber(1.2, 3.5);
+        ComplexNumber temp = sum(c1, c2);
+        System.out.printf("Sum is: "+ temp.real+" + "+ temp.img +"i");
+    }
+}
diff --git a/palindrome-checker.java b/palindrome-checker.java
new file mode 100644
index 0000000..705ce89
--- /dev/null
+++ b/palindrome-checker.java
@@ -0,0 +1,24 @@
+import java.util.Scanner;
+class PalindromeExample
+{  
+	public static void main(String args[])
+	{  
+  		int r,sum=0,temp;    
+  		int n;
+
+  		Scanner sc = new Scanner(System.in);
+  		System.out.println("Enter the number:");
+  		n = sc.nextInt();  
+  		temp=n;    
+  		while(n>0)
+  		{    
+   			r=n%10;   
+   			sum=(sum*10)+r;    
+   			n=n/10;    
+  		}    
+  		if(temp==sum)    
+   		System.out.println("palindrome number ");    
+  		else    
+   		System.out.println("not palindrome");    
+	}  
+}  
diff --git a/wordshash.java b/wordshash.java
new file mode 100644
index 0000000..2a47064
--- /dev/null
+++ b/wordshash.java
@@ -0,0 +1,22 @@
+import java.util.HashMap;
+ 
+public class FinalCountWords {
+ 
+    public static void main(String[] args) {
+        String str = "This this is is done by Saket Saket";
+        String[] split = str.split(" ");
+         
+                HashMap<String,Integer> map = new HashMap<String,Integer>();
+        for (int i=0; i<split.length; i++) {
+            if (map.containsKey(split[i])) {
+                int count = map.get(split[i]);
+                map.put(split[i], count+1);
+            }
+            else {
+                map.put(split[i], 1);
+            }
+        }
+        System.out.println(map);
+    }
+ 
+}