Java.util.Arrays.binarySearch() Method



The java.util.Arrays.binarySearch(double[] a, double key) method searches the specified array of doubles for the specified value using the binary search algorithm.The array must be sorted before making this call.If it is not sorted, the results are undefined.


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

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


  • 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.




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

package com.tutorialspoint;

import java.util.Arrays;

public class ArrayDemo4 {
   public static void main(String[] args) {

      // initializing unsorted double array
      double doubleArr[] = {5.4,4.6,49.2,9.2,35.4};

      // sorting array

      // let us print all the elements available in list
      System.out.println("The sorted double array is:");
      for (double number : doubleArr) {
         System.out.println("Number = " + number);

      // entering the value to be searched
      double searchVal = 5.4;

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

      System.out.println("The index of element 5.4 is : " + retVal);

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

The sorted double array is:
Number = 4.6
Number = 5.4
Number = 9.2
Number = 35.4
Number = 49.2
The index of element 5.4 is : 1