Java program for binary search
Java program for binary search: This code implements binary search algorithm. Please note input numbers must be in ascending order.
Java programming code
import java.util.Scanner;
class BinarySearch
{
public static void main(String args[])
{
int c, first, last, middle, n, search, array[];
Scanner in = new Scanner(System.in);
System.out.println("Enter number of elements");
n = in.nextInt();
array = new int[n];
System.out.println("Enter " + n + " integers");
for (c = 0; c < n; c++)
array[c] = in.nextInt();
System.out.println("Enter value to find");
search = in.nextInt();
first = 0;
last = n - 1;
middle = (first + last)/2;
while( first <= last )
{
if ( array[middle] < search )
first = middle + 1;
else if ( array[middle] == search )
{
System.out.println(search + " found at location " + (middle + 1) + ".");
break;
}
else
last = middle - 1;
middle = (first + last)/2;
}
if ( first > last )
System.out.println(search + " isn't present in the list.\n");
}
}
Other methods of searching are Linear search and Hashing. There is a binarySearch method in Arrays class which can also be used.
import java.util.Arrays;
class BS
{
public static void main(String args[])
{
char characters[] = { 'a', 'b', 'c', 'd', 'e' };
System.out.println(Arrays.binarySearch(characters, 'a'));
System.out.println(Arrays.binarySearch(characters, 'p'));
}
}
binarySearch method returns the location if a match occurs otherwise -(x+1) where x is the no. of elements in the array, For example, in the second case above when p isn't present in characters array the returned value will be -6.
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