Binary Search.java

// Binary Search Practice/ Implementation
package binarySearch;

import java.util.Scanner;

public class BinarySearchMain {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println("Enter n i.e total number of elements in array");
		int n=sc.nextInt();
		
		int arr[] =new int[n];
		System.out.println("enter "+n+" numbers in sorted array:");
		for(int i=0;i<n;i++)
			arr[i]=sc.nextInt();
		System.out.println("Enter a number to find in the array :");
		int num =sc.nextInt();
		
		sc.close();
		
		// creating object of class binary search 
		BinarySearch obj = new BinarySearch();
		int res = obj.binarySearch(arr,0,n-1,num);
		if(res==-1)
			System.out.println("Number not found");
		else
			System.out.println("number found at index : "+res);
		
	}
}
	
	class BinarySearch{
		int binarySearch(int arr[],int l, int r, int x) {
			
			if(r>=l) {
				
				int mid=(l+r)/2;
				if(arr[mid]==x)
					return mid;
				if(arr[mid]>x)						// if given number is less than mid of the array
					return binarySearch(arr, l, mid-1, x);
				
				return binarySearch(arr, mid+1, r, x);
			}
			// the given number is not present in the array
			return -1;
		}
	}