Java CSV reader/writer advice?

import java.io.*;
import java.util.ArrayList;
public class CSVData {
	public ArrayList<String[]> readCSV(String filename) throws Exception {
		BufferedReader reader = new BufferedReader(new FileReader(filename));
		ArrayList<String[]> rows = new ArrayList<String[]>();
		String line = reader.readLine();
		while(line != null) {
			String[] row = line.split(",");
			for (int x = 0; x<row.length; x++) {
				row[x] = row[x].trim(); 
			}
			rows.add(row);
			line = reader.readLine();
		}
		return rows;
	}
	public void writeCSV(ArrayList<String[]> data, String filename) throws Exception {
		FileWriter writer = new FileWriter(filename);
		for (int x = 0; x < data.size(); x++) {
			String[] line = data.get(x);
			for (int y = 0; y < line.length; y++) {
				if (y < line.length-1) {
					writer.append(line[y]+",\t");
				} else {
					writer.append(line[y]);
				}
			}
			writer.append("\n");
		}
		writer.flush();
		writer.close();
	}
}