Java.util.Arrays.binarySearch() Method

Description

The java.util.Arrays.binarySearch(Object[] a, Object key) method searches the specified array for the specified object using the binary search algorithm.The array be sorted into ascending order according to the natural ordering of its elements prior to making this call. If it is not sorted, the results are undefined.

Declaration

Following is the declaration for java.util.Arrays.binarySearch() method

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

Parameters

• a -- This is the array to be searched.

• key -- This is the value to be searched for.

Return Value

This method returns index of the search key, if it is contained in the array, else it returns (-(insertion point) - 1). The insertion point is the point at which the key would be inserted into the array: the index of the first element greater than the key, or a.length if all elements in the array are less than the specified key.

Exception

• ClassCastException -- If the search key is not comparable to the elements of the array.

Example

The following example shows the usage of java.util.Arrays.binarySearch() method.

package com.tutorialspoint;

import java.util.Arrays;

public class ArrayDemo {
 
   public static void main(String[] args) {

    // initializing unsorted array
    Object arr[] = {10,2,22,69};

    // sorting array
    Arrays.sort(arr);

    // let us print all the elements available
    System.out.println("The sorted array is:");
    for (Object number : arr) {
      System.out.println("Number = " + number);
    }

    // entering the value to be searched
    int searchVal = 22;

    int retVal = Arrays.binarySearch(arr,searchVal);

    System.out.println("The index of element 22 is : " + retVal);
  }
}

Let us compile and run the above program, this will produce the following result:

The sorted array is:
Number = 2
Number = 10
Number = 22
Number = 69
The index of element 22 is : 2