Sorting and Binary search using Java

Question

I was asked to sort and search an array. The sorting the array was simple and my code worked but then whenever I try to call the binary search method it works for the first

Answer 1

You did a mistake in calling the rBsearch method in the following lines Instead of

else if (L[mid] < k) {
        return rBsearch(L, k, mid + 1, high); 
    } else {
        return rBsearch(L, k, low, mid - 1);
    }

You should use

else if (L[mid] < k) {
            return rBsearch(L,  mid + 1, high,k); //the order of the parameters
        } else {
            return rBsearch(L, low, mid - 1,k);
        }

Answer 2

You goofed up the binary search intervals

public static int rBsearch(int[] L, int low, int high, int k) {


    int mid = (low + high) / 2;

    if (low > high) {
        return -1;
    } else if (L[mid] == k) {
        return L[mid];
    } else if (L[mid] < k) {
        return rBsearch(L, mid + 1, high, k);
    } else {
        return rBsearch(L, low, mid - 1, k);
    }
 }

Answer 3

1. Take Array From User
2. Sort Array using Build-in Function of Java...

3. then Search Element using Binary Search....

       import java.lang.reflect.Array;
       import java.util.Arrays;
       import java.util.Scanner;
   
       class BinarySearch
       {
          public static void main(String args[])
          {
             int array[];
   
             Scanner input = new Scanner(System.in);
             System.out.println("Enter number of elements:");
            int Size_Of_Array = input.nextInt(); 
   
   
             array = new int[Size_Of_Array];
   
             System.out.println("Enter " + Size_Of_Array + " integers");
   
             for (int counter = 0; counter < Size_Of_Array; counter++)
                 array[counter] = input.nextInt();
   
             Arrays.sort(array);
             System.out.println("Sorting Array is :-");
             for (int counter = 0; counter < Size_Of_Array; counter++)
                 System.out.println(array[counter]);
   
             System.out.println("Enter the search value:");
             int  Searching_item = input.nextInt();
   
             int First_Index=0;
             int Last_Index=Size_Of_Array-1;
             int Middle_Index=(First_Index+Last_Index)/2;
   
             while(First_Index <= Last_Index)
             {
                 if(array[Middle_Index] < Searching_item)
                 {
                     First_Index=Middle_Index+1;
                 }
                 else if ( array[Middle_Index] == Searching_item ) 
                 {
                   System.out.println(Searching_item + " found at location " + (Middle_Index + 1) + ".");
                   break;
                 }
                 else
                 {
                     Last_Index = Middle_Index - 1;
                 }
                 Middle_Index = (First_Index + Last_Index)/2;
   
                 if ( First_Index > Last_Index )
                 {
                     System.out.println(Searching_item + " is not found.\n");
                 }
             }
           }
       }
   

   Result of BinarySearch

Answer 4

Easiest way is: Convert you array to list: Arrays.asList(array)

For sort: Collections#sort

For search: Collections#binarySearch

See this