java.util.Collections.binarySearch() Method

---

Description

The binarySearch(List<? extends Comparable<? super T>>, T) method is used to search the specified list for the specified object using the binary search algorithm.

Declaration

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

public static <T> int binarySearch(List<? extends Comparable<? super T>> list,   T key)

Parameters

• list − This is the list to be searched.

• key − This is the key to be searched for.

Return Value

The method call returns the index of the search key, if it is contained in the list.

Exception

ClassCastException − This is thrown if the list contains elements that are not mutually comparable.

Example

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

package com.tutorialspoint;

import java.util.*;

public class CollectionsDemo {
   public static void main(String args[]) {
   
      // create arraylist       
      ArrayList<String> arlst = new ArrayList<String>();

      // populate the list
      arlst.add("TP");
      arlst.add("PROVIDES");
      arlst.add("QUALITY");
      arlst.add("TUTORIALS");

      // search the list for key 'QUALITY'
      int index = Collections.binarySearch(arlst, "QUALITY");     

      System.out.println("'QUALITY' is available at index: "+index);
   }    
}

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

'QUALITY' is available at index: 2