Collections method binarySearch. - Java Collection Framework

Java examples for Collection Framework:Collections Utility Methods

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Description

Collections method binarySearch.

Demo Code


import java.util.List;
import java.util.Arrays;
import java.util.Collections;
import java.util.ArrayList;

public class Main 
{
   public static void main(String[] args)
   {//from ww w  .ja  va2s .  c  om
      // create an ArrayList<String> from the contents of colors array
      String[] colors = {"red", "white", "blue", "black", "yellow", 
         "purple", "tan", "pink"};
      List<String> list = 
         new ArrayList<>(Arrays.asList(colors));

      Collections.sort(list); // sort the ArrayList
      System.out.printf("Sorted ArrayList: %s%n", list);

      // search list for various values
      printSearchResults(list, "black"); // first item
      printSearchResults(list, "red"); // middle item
      printSearchResults(list, "pink"); // last item
      printSearchResults(list, "aqua"); // below lowest
      printSearchResults(list, "gray"); // does not exist
      printSearchResults(list, "teal"); // does not exist
   }      

   // perform search and display result
   private static void printSearchResults(
      List<String> list, String key)
   {
      int result = 0;

      System.out.printf("%nSearching for: %s%n", key);
      result = Collections.binarySearch(list, key);
      
      if (result >= 0)
         System.out.printf("Found at index %d%n", result);
      else
         System.out.printf("Not Found (%d)%n",result);
   } 
}

Result


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