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Performing Binary Search on Java int Array Example

  1. /*
  2.   Performing Binary Search on Java int Array Example
  3.   This java example shows how to perform binary search for an element of
  4.   java int array using Arrays class.
  5. */
  6.  
  7. import java.util.Arrays;
  8.  
  9. public class BinarySearchIntArrayExample {
  10.  
  11.   public static void main(String[] args) {
  12.     //create int array
  13.     int intArray[] = {1,2,4,5};
  14.    
  15.     /*
  16.       To perform binary search on int array use
  17.       int binarySearch(int[] b, int value) of Arrays class. This method searches
  18.       the int array for specified int value using binary search algorithm.
  19.      
  20.       Please note that the int array MUST BE SORTED before it can be searched
  21.       using binarySearch method.
  22.      
  23.       This method returns the index of the value to be searched, if found in the
  24.       array.
  25.       Otherwise it returns (- (X) - 1)
  26.       where X is the index where the the search value would be inserted.
  27.       i.e. index of first element that is grater than the search
  28.       value or array.length, if all elements of an array are less than
  29.       the search value.
  30.     */
  31.    
  32.     //sort int array using Arrays.sort method
  33.     Arrays.sort(intArray);
  34.    
  35.     //value to search
  36.     int searchValue = 2;
  37.    
  38.     //since 2 is present in int array, index of it would be returned
  39.     int intResult = Arrays.binarySearch(intArray,searchValue);
  40.     System.out.println("Result of binary search of 2 is : " + intResult);
  41.    
  42.     //lets search something which is not in int array !
  43.     searchValue = 3;
  44.     intResult = Arrays.binarySearch(intArray,searchValue);
  45.     System.out.println("Result of binary search of 3 is : " + intResult);
  46.  
  47.   }
  48. }
  49.  
  50. /*
  51. Output would be
  52. Result of binary search of 2 is : 1
  53. Result of binary search of 3 is : -3
  54. */