Prints out all binary values from 0 to 2^n. BinaryStrings is my method, and FastBinaryStrings (hah) is the method I found on Stack Overflow

lab14.java

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/**
 * Class: CSC 190
 * Date: 11/22/2013
 * Project: 
 * @author Wes Gilleland
 * Purpose: 
 */

import org.apache.commons.lang.time.StopWatch;

class BinaryStrings {

	/**
	 * Prints every binary value from 0 to 2^n
	 *
	 * @param n The n of 2^n
	 */
	public static void printBinary(int n) {
		long number = 1;
		String s = "";

		/*
		 * Prep the binary string to have n number of zeroes and find 2^n
		 */
		for (int i = 0; i < n; i++) {
			s += "0";
			number *= 2;
		}

		/*Print the zeroes*/
		System.out.println(s);

		/*Print all the other binary numbers*/
		for (int i = 0; i < number - 1; i++) {
			s = incrementBinary(s);
			System.out.println(s);
		}
	}

	/**
	 * Takes in a string of binary and increments it by 1
	 *
	 * @param binary The binary string to increment
	 * @return The incremented binary string
	 */
	public static String incrementBinary(String binary) {
		int length = binary.length();
		int currentPosition = length - 1;

		/*
		 * While the current character is not at '0', keep replacing the current character with a '0'
		 */
		while (binary.charAt(currentPosition) != '0') {
			binary = replace(binary, currentPosition, "0");
			currentPosition--;
		}
		return replace(binary, currentPosition, "1");
	}

	/**
	 * Replaces a character in a given string at a given position
	 *
	 * @param inputString       The string to replace
	 * @param insertPosition    The position of the character to insert
	 * @param characterToInsert The character to insert
	 * @return The modified string
	 */
	private static String replace(String inputString, int insertPosition, String characterToInsert) {
		int length = inputString.length();
		if (insertPosition == length) {
			return inputString.substring(length - 1) + characterToInsert; /*//replace the character at the end of the string*/
		} else if (insertPosition == 0) {
			return characterToInsert + inputString.substring(1); /*//replace the character at the beginning of the string*/
		}
		return inputString.substring(0, insertPosition) + characterToInsert + inputString.substring(insertPosition + 1, length); /*// replace the character in the middle of the string*/
	}
}

class FastBinaryStrings {
	public static void doStuff(long num1, long num2) {
		for (long i = 0; i < num2; i++) {
			String result = "";
			for (long j = num1; j > 0; j >>= 1) {
				if ((j & i) != 0) {
					result += "1";
				} else {
					result += "0";
				}
			}
			System.out.println(result);
		}
	}
}

public class lab14 {
	public static void main(String[] args) {
		StopWatch stopwatch = new StopWatch();
		/*Scanner in = new Scanner(System.in);
		BinaryStrings myBS = new BinaryStrings();

		System.out.print("Enter a positive integer: ");
		myBS.printBinary(in.nextInt());*/
		int n = 22;
		long num1 = (long) Math.pow(2, n);
		long num2 = num1 * 2;

		long time1;
		long time2;
		String format = "Time for %s to do %d bits: %10.3f seconds%n";

		stopwatch.start();
		FastBinaryStrings.doStuff(num1, num2);
		stopwatch.stop();
		time1 = stopwatch.getTime();

		stopwatch.reset();

		stopwatch.start();
		BinaryStrings.printBinary(n);
		stopwatch.stop();
		time2 = stopwatch.getTime();

		System.out.printf(format, "FastBinaryStrings", n, (float) time1 / 1000);
		System.out.printf(format, "BinaryStrings", n, (float) time2 / 1000);

	}
}