import java.io.*;

public class Whatever {
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		File target = new File("test.txt");
		String lineToWrite = "a new line";
		try {
			FileWriter writer = new FileWriter(target, true); // This opens the file in append mode
			writer.write(lineToWrite + "\n");
			writer.close();
		} catch (IOException e) {
			//Throw it as a runtimeexception to exit the program
			throw new RuntimeException(e);
		}
	}

}