FileLines.java

package kb.howtokb.utils;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Iterator;

/**
 * An iterator over a file, line by line (simulates calling bufferedReader.readLine()).
 * @author ntandon
 *
 */
public class FileLines implements Iterable<String> {

	private BufferedReader br;

	public FileLines(String filePath) throws FileNotFoundException {
		br =
			new BufferedReader(new InputStreamReader(new FileInputStream(
				new File(filePath))));
	}

	public static int countLines(String filePath) throws FileNotFoundException {
		int ctr = 0;
		for (String l : new FileLines(filePath)) {
			ctr++;
		}
		return ctr;
	}

	@Override
	protected void finalize() throws Throwable {
		super.finalize();
		if (br != null)
			br.close();
	}

	@Override
	public Iterator<String> iterator() {

		return new Iterator<String>() {

			String line;

			@Override
			public boolean hasNext() {
				try {
					if (br == null || !br.ready())
						return false;
					line = br.readLine();
				} catch (IOException e) {
					e.printStackTrace();
				}

				if (line == null) {
					try {
						br.close();
					} catch (IOException e) {
						e.printStackTrace();
					}
				}
				return line != null;
			}

			@Override
			public String next() {
				return line;
			}

			@Override
			public void remove() {
				throw new UnsupportedOperationException(
					"Not yet implemented FileLines.remove()");
			}
		};
	}

}