Static Generic Iterative Binary Search Algorithm In Java

In order take advantage of Generics in Java, binary search method can be implemented generically.

Binary search works for sorted Arrays so Arrays.sort method is used before using binarySearch method.

Any type that implements Comparable interface is accepted by the generic iterative search method.

Built-in String, Integer and Double classes in Java implement Comparable interface so search method accepts these parameters.

package basics;

import java.util.Arrays;

public class GenericIterativeBinarySearch {

 public static <T extends Comparable<T>> boolean search( T[] items, T item ) {

  if (item == null) {
   return false;
  }

  int low = 0;
  int high = items.length - 1;

  while (low <= high) {

   int ix = low + (high - low) / 2;

   if (item.compareTo(items[ix]) < 0) {
    high = ix - 1;
   } else if (item.compareTo(items[ix]) > 0) {
    low = ix + 1;
   } else {
    return true;
   }
  }

  return false;
 }


 public static void main(String[] args) {

  Integer[] items = { 22, 55, 66, 11, 32, 56, 67, 89, 95, 10 };

  Arrays.sort(items);

  boolean found = search(items, Integer.valueOf(22) );
  System.out.println("Integer Array Contains item 22 = "+found);

  found = search(items, Integer.valueOf(11) );
  System.out.println("Integer Array Contains item 11 = "+found);

  found = search(items, Integer.valueOf(67) );
  System.out.println("Integer Array Contains item 67 = "+found);

  found = search(items, Integer.valueOf(10) );
  System.out.println("Integer Array Contains item 10 = "+found);

  found = search(items, Integer.valueOf(101) );
  System.out.println("Integer Array Contains item 101 = "+found);  
  
  found = search(items, null );
  System.out.println("Integer Array Contains item null = "+found); 
  
  String[] strItems = { "alk", "abc", "adk", "zyt", "fre", "nhy" };
  Arrays.sort(strItems);
  
  found = search( strItems, "alk" );
  System.out.println("String Array Contains item alk = "+found);
  
  found = search( strItems, "nhy" );
  System.out.println("String Array Contains item nhy = "+found);
  
  found = search( strItems, "zyt" );
  System.out.println("String Array Contains item zyt = "+found);
  
  found = search( strItems, "zyts" );
  System.out.println("String Array Contains item zyts = "+found);
  
  found = search( strItems, "null" );
  System.out.println("String Array Contains item null = "+found);
  
  Double[] dItems = { 11.3, 13.3, 6.0, 9.6, 45.7, 23.2 };
  Arrays.sort(dItems);
  
  found = search( dItems, 13.3 );
  System.out.println("Double Array Contains item 13.3 = "+found);
  
  found = search( dItems, 14.3 );
  System.out.println("Double Array Contains item 14.3 = "+found);
  
  found = search( dItems, 23.0 );
  System.out.println("Double Array Contains item 23.0 = "+found);  
  
 }
}

Create a GenericIterativeBinarySearch.java file in your workspace.

When the main method inside the GenericIterativeBinarySearch class executed it is going to print :

Integer Array Contains item 22 = true
Integer Array Contains item 11 = true
Integer Array Contains item 67 = true
Integer Array Contains item 10 = true
Integer Array Contains item 101 = false
Integer Array Contains item null = false
String Array Contains item alk = true
String Array Contains item nhy = true
String Array Contains item zyt = true
String Array Contains item zyts = false
String Array Contains item null = false
Double Array Contains item 13.3 = true
Double Array Contains item 14.3 = false
Double Array Contains item 23.0 = false