Example Program to perform binary search on a list of integer numbers
This program uses binary search algorithm to search an element in given list of elements.
/* Program: Binary Search Example
* Written by: Chaitanya from beginnersbook.com
* Input: Number of elements, element's values, value to be searched
* Output:Position of the number input by user among other numbers*/
import java.util.Scanner;
class BinarySearchExample
{
public static void main(String args[])
{
int counter, num, item, array[], first, last, middle;
//To capture user input
Scanner input = new Scanner(System.in);
System.out.println("Enter number of elements:");
num = input.nextInt();
//Creating array to store the all the numbers
array = new int[num];
System.out.println("Enter " + num + " integers");
//Loop to store each numbers in array
for (counter = 0; counter < num; counter++)
array[counter] = input.nextInt();
System.out.println("Enter the search value:");
item = input.nextInt();
first = 0;
last = num - 1;
middle = (first + last)/2;
while( first <= last )
{
if ( array[middle] < item )
first = middle + 1;
else if ( array[middle] == item )
{
System.out.println(item + " found at location " + (middle + 1) + ".");
break;
}
else
{
last = middle - 1;
}
middle = (first + last)/2;
}
if ( first > last )
System.out.println(item + " is not found.\n");
}
}
Output 1:
Enter number of elements: 7 Enter 7 integers 4 5 66 77 8 99 0 Enter the search value: 77 77 found at location 4.
Output 2:
Enter number of elements: 5 Enter 5 integers 12 3 77 890 23 Enter the search value: 99 99 is not found.
Ashrumochan Senapati says
May 14, 2014 at 4:07 AMWhy you are still using the old approach for binary search.
Directly we can use the utility methods of utility class – java.util.Arrays
Methods Example-
===============
public static int binarySearch(primitive() p,Primitive key)
public static int binarySearch(Object() o,Object key)
public static int binarySearch(Object() o,Object key,Comparator c)
Srinivas Reddy says
July 17, 2014 at 12:02 PMThanks Ashrumochan for your suggestion. It works fine and great share……
Deepak Raj says
July 17, 2014 at 12:03 PMNice one.. Thanks.
Lueos Joshef says
November 11, 2014 at 8:03 AMThanks Ashrumochan Senapati,Good to know about “java.util.Arrays” class. Really helped a lot…
You made my day!!!
maulik says
April 14, 2015 at 1:09 PMi found array index out of bound exception while executing this code.give me solution for that.
krishna says
August 31, 2015 at 5:55 AMI just requesting a clarification , In my binary search algorithm classes it has been told that , if sort is not done before a Binary search it is almost equal to Linear search . In this example sorting of array is not done(Please correct me if I am missing something ) .
Jagriti says
September 7, 2015 at 4:26 PMYes, as far as i know me too think sorting is required. This program gives false output if u search for the value 8 considering the above numbers
RAM says
October 16, 2015 at 1:55 AMYes..Sorting is prerequisite for Binary Search.
kishor singh says
January 7, 2016 at 5:56 PMEnter number of elements:
6
Enter 6 integers
12
3
5
7
9
4
Enter the search value:
4
4 is not found.
Javed says
April 22, 2016 at 6:02 AMThis is not binary search.. The basic requirement of binary search should be a presorted array in ascending order if iam not wrong…
Preeti says
May 9, 2017 at 6:18 PMYes , we should sort before searching the element.
Arrays.sort(array)
Otherwise above program wont work