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Java Array Binary Search example
Posted on: October 22, 2009 at 12:00 AM
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Learn how to implement binary search code on Java Arrays object

Java Array Binary Search

  • It is a method for searching the array element in the given arrays.
  • It is a static method of the class Arrays.
  • It uses the binary search algorithm. 
  • It returns the index of the found element, but if element is not found then returns -1.
  • Array can be of any data type object.

Syntax
public static int binarySearch(Object[] a, Object key)

Array used in binarySearch must be sorted. The binarsearch() method with Unsorted arrays give wrong result. Array having duplicate elements when searched by binarySearch() function may return any of the duplicate element.

Following example demonstrates how to do a binary search on the Java array object


 import java.util.Arrays;

public class binary_search {

    public static void main(String[] args) {
           int ar1[]={2,44,5,66,78,90,23,66};
           int p, key=78;
           p=Arrays.binarySearch(ar1, key);
           System.out.println("element found at index "+p);
           Arrays.sort(ar1);
           p=Arrays.binarySearch(ar1, key);
           System.out.println("element found at index "+p);     
    }
}

Output
 
element found at index 4
element found at index 6

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Posted on: October 22, 2009

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