Difference between revisions of "LineReaderIterator"

package org.darkmine.util.io;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.util.Iterator;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class provides an iterator pattern over a given input stream, returning each line as a String.
 * 
 * @author Andy
 *
 */
public class LineReaderIterator implements Iterator<String> {
	
	private static final Logger log = LoggerFactory.getLogger(LineReaderIterator.class);
	private LineNumberReader lnr;
	private String nextLine;
	
	/**
	 * Create an iterator on the given stream.
	 * 
	 * @param inputStream The input stream.
	 */
	public LineReaderIterator(InputStream inputStream) {
		lnr = new LineNumberReader( new BufferedReader( new InputStreamReader( inputStream ) ) );
		try {
			nextLine = lnr.readLine();
		} catch (IOException e) {
			log.error( "Failed to read line (near line " + lnr.getLineNumber() + ")" , e );
			nextLine = null;
		}
	}

	/**
	 * @see java.util.Iterator#hasNext()
	 */
	public boolean hasNext() {
		return nextLine != null;
	}

	/**
	 * @see java.util.Iterator#next()
	 */
	public String next() {
		String line = nextLine;
		try {
			nextLine = lnr.readLine();
		} catch (IOException e) {
			nextLine = null;
			log.error( "Failed to read line (near line " + lnr.getLineNumber() + ")" , e );
		}
		return line;
	}

}