Example of implementing binary search.

BinarySearch.java

import java.io.*;

public class BinarySearch
{

	public int[] a;

	public BinarySearch()
	{
		a = new int[] { 0, 1, 2, 3, 4, 8, 10, 14 };
	}

	private int bin_search( int val, int beg, int end )
	{
		int mid = (beg + end) / 2;

		if( a[mid] == val )
			return mid;

		if( beg >= end )
			return -1;

		if( val < a[mid] )
			end = mid - 1;
		else
			beg = mid + 1;

		return bin_search( val, beg, end );
	}

	public static void main( String[] args ) throws IOException
	{
		BinarySearch bs = new BinarySearch();

		BufferedReader br = new BufferedReader( new InputStreamReader( System.in ) );
		String input = " ";

		while( input.charAt(0) != 'q' ) {
			System.out.println( "Enter a number to search for: " );
			input = br.readLine();

			if( input.charAt(0) == 'q' )
				break;

			int val = Integer.parseInt( input );
			System.out.println( "Index of value in array: " + bs.bin_search( val, 0, bs.a.length - 1 ) );
		}
	}
}