Also added basic example_java

Armstrong.java

@@ -0,0 +1,28 @@
+import java.util.Scanner;
+public class Armstrong {
+
+	public static void main(String[] args) {
+      Scanner s=new Scanner(System.in);
+      		int n=s.nextInt();
+		int c=n;
+      int z=n;
+		int sum=0,count=0;
+      while(n>0){
+        n=n/10;
+        count++;
+      }
+		while(z>0) {
+			int v=z%10;
+			z=z/10;
+			sum+=Math.pow(v, count);
+		}
+		if(sum==c) {
+			System.out.println("true");
+		}
+		else {
+			System.out.println("false");
+
+
+	}
+}
+}

ArrangeArray.java

@@ -0,0 +1,25 @@
+import java.util.Scanner;
+
+public class ArrangeArray {
+	public static void main(String[] args) {
+		Scanner s=new Scanner(System.in);
+		int n=s.nextInt();
+		int[]arr=new int[n];
+		int i=0,j=0;
+		int left=0,right=n-1;
+		for(i=1;i<=n;i++) {
+			if(i%2==1) {
+				arr[left]=i;
+				left++;
+			}
+			else if(i%2==0) {
+				arr[right]=i;
+				right--;
+			}
+		}
+		for(j=0;j<n;j++) {
+			System.out.print(arr[j]);
+		}
+	}
+
+}

BinarySearch.java

@@ -0,0 +1,38 @@
+import java.util.Scanner;
+
+public class BinarySearch {
+	public static void main(String[] args) {
+		Scanner s=new Scanner(System.in);
+		int n=s.nextInt();
+		int [] arr=new int[n];
+		Construct(arr);
+		int a=s.nextInt();
+		int x=Search(arr,a);
+		System.out.println(x);
+	}
+	static int[] Construct(int[]arr) {
+		Scanner s=new Scanner(System.in); 
+		for(int i=0;i<arr.length;i++) {
+			arr[i]=s.nextInt();
+		}
+		return arr;
+	}
+	static int Search(int[] arr,int a) {
+		int start=0,end=arr.length-1;
+		int mid=0;
+		while(start<=end) {
+			mid=(start+end)/2;
+			if(arr[mid]<a) {
+				start=mid+1;
+			}
+			else if(arr[mid]>a) {
+				end=mid-1;
+			}
+			else {
+				return mid;
+			}
+		}
+		return -1;
+	}
+
+}

BubbleSort.java

@@ -0,0 +1,35 @@
+import java.util.Scanner;
+
+public class BubbleSort {
+	public static void main(String[] args) {
+		Scanner s=new Scanner(System.in);
+		int n=s.nextInt();
+		int[] arr=new int[n];
+		arr=Construct(arr);
+		Sort(arr);
+	}
+	static int[] Construct(int[]arr) {
+		Scanner s=new Scanner(System.in); 
+		for(int i=0;i<arr.length;i++) {
+			arr[i]=s.nextInt();
+		}
+		return arr;
+	}
+	static void Sort(int[]arr) {
+		for(int i=arr.length;i>0;i--) {
+			for(int j=0;j<i;j++) {
+				if(j+1<i&&arr[j]>=arr[j+1]) {
+					int temp;
+					temp=arr[j];
+					arr[j]=arr[j+1];
+					arr[j+1]=temp;
+				}
+			}
+		}
+		for(int k=0;k<arr.length;k++) {
+			System.out.print(arr[k]);
+		}
+
+	}
+
+}

factorial_recursion.cpp

@@ -0,0 +1,23 @@
+#include<iostream>
+using namespace std;
+
+int factorial(int n);
+
+int main()
+{
+    int n;
+
+    cout << "Enter a positive integer: ";
+    cin >> n;
+
+    cout << "Factorial of " << n << " = " << factorial(n);
+
+    return 0;
+}
+int factorial(int n)
+{
+    if(n > 1)
+        return n * factorial(n - 1);
+    else
+        return 1;
+}