Counting Source Code lines in a Java file

SourceCodeLineCounter.java

package examples;

import java.io.BufferedReader;
import java.io.IOException;

/**
 * This class  counts the number of source code lines by excluding comments, in a Java file
 * The pseudocode is as below
 * 
 * Initial: Set count = 0, commentBegan = false
 * Start: Read line
 * Begin: If line is not null, goto Check, else goto End
 * Check: If line is a trivial line(after trimming, either begins with // or is ""), goto Start
 *        If commentBegan = true
 *             if comment has not ended in line 
 *                goto Start
 *              else 
 *                line = what remains in the line after comment ends
 *                commenBegan = false
 *                if line is trivial
 *                   goto Start
 * 		  If line is a valid source code line, count++
 *        If comment has begun in the line, set commentBegan = true
 *        goto Start
 * End: print count
 */
public class SourceCodeLineCounter {
	public static int getNumberOfLines(BufferedReader bReader)
			throws IOException {
		int count = 0;
		boolean commentBegan = false;
		String line = null;

		while ((line = bReader.readLine()) != null) {
			line = line.trim();
			if ("".equals(line) || line.startsWith("//")) {
				continue;
			}
			if (commentBegan) {
				if (commentEnded(line)) {
					line = line.substring(line.indexOf("*/") + 2).trim();
					commentBegan = false;
					if ("".equals(line) || line.startsWith("//")) {
						continue;
					}
				} else
					continue;
			}
			if (isSourceCodeLine(line)) {
				count++;
			}
			if (commentBegan(line)) {
				commentBegan = true;
			}
		}
		return count;
	}
	
	/**
	 * 
	 * @param line
	 * @return This method checks if in the given line a comment has begun and has not ended
	 */
	private static boolean commentBegan(String line) {
		// If line = /* */, this method will return false
		// If line = /* */ /*, this method will return true
		int index = line.indexOf("/*");
		if (index < 0) {
			return false;
		}
		int quoteStartIndex = line.indexOf("\"");
		if (quoteStartIndex != -1 && quoteStartIndex < index) {
			while (quoteStartIndex > -1) {
				line = line.substring(quoteStartIndex + 1);
				int quoteEndIndex = line.indexOf("\"");
				line = line.substring(quoteEndIndex + 1);
				quoteStartIndex = line.indexOf("\"");
			}
			return commentBegan(line);
		}
		return !commentEnded(line.substring(index + 2));
	}
	
	/**
	 * 
	 * @param line
	 * @return This method checks if in the given line a comment has ended and no new comment has not begun
	 */ 
	private static boolean commentEnded(String line) {
		// If line = */ /* , this method will return false
		// If line = */ /* */, this method will return true
		int index = line.indexOf("*/");
		if (index < 0) {
			return false;
		} else {
			String subString = line.substring(index + 2).trim();
			if ("".equals(subString) || subString.startsWith("//")) {
				return true;
			}
			if(commentBegan(subString))
			{
				return false;
			}
			else
			{
				return true;
			}
		}
	}

	/**
	 * 
	 * @param line
	 * @return This method returns true if there is any valid source code in the given input line. It does not worry if comment has begun or not.
	 * This method will work only if we are sure that comment has not already begun previously. Hence, this method should be called only after {@link #commentBegan(String)} is called
	 */
	private static boolean isSourceCodeLine(String line) {
		boolean isSourceCodeLine = false;
		line = line.trim();
		if ("".equals(line) || line.startsWith("//")) {
			return isSourceCodeLine;
		}
		if (line.length() == 1) {
			return true;
		}
		int index = line.indexOf("/*");
		if (index != 0) {
			return true;
		} else {
			while (line.length() > 0) {
				line = line.substring(index + 2);
				int endCommentPosition = line.indexOf("*/");
				if (endCommentPosition < 0) {
					return false;
				}
				if (endCommentPosition == line.length() - 2) {
					return false;
				} else {
					String subString = line.substring(endCommentPosition + 2)
							.trim();
					if ("".equals(subString) || subString.indexOf("//") == 0) {
						return false;
					} else {
						if (subString.startsWith("/*")) {
							line = subString;
							continue;
						}
						return true;
					}
				}

			}
		}
		return isSourceCodeLine;
	}
}