Java: Reading and writing text files

package pritom;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * User: pritom
 * Date: 14/12/12
 * Time: 9:28 AM
 * To change this template use File | Settings | File Templates.
 */
public class ReadWriteTextFileJDK7 {

    public static void main(String... aArgs) throws IOException {
        ReadWriteTextFileJDK7 text = new ReadWriteTextFileJDK7();

        //treat as a small file
        List<String> lines = text.readSmallTextFile(FILE_NAME);
        log(lines);
        lines.add("This is a line added in code.");
        text.writeSmallTextFile(lines, FILE_NAME);

        //treat as a large file - use some buffering
        text.readLargerTextFile(FILE_NAME);
        lines = Arrays.asList("Line added #1", "Line added #2");
        text.writeLargerTextFile(OUTPUT_FILE_NAME, lines);
    }

    final static String FILE_NAME = "C:/tmp/input.txt";
    final static String OUTPUT_FILE_NAME = "C:/tmp/output.txt";
    final static Charset ENCODING = StandardCharsets.UTF_8;

    //For smaller files

    List<String> readSmallTextFile(String aFileName) throws IOException {
        System.out.print("***** readSmallTextFile *****\n");
        Path path = Paths.get(aFileName);
        return Files.readAllLines(path, ENCODING);
    }

    void writeSmallTextFile(List<String> aLines, String aFileName) throws IOException {
        System.out.print("***** writeSmallTextFile *****\n");
        Path path = Paths.get(aFileName);
        Files.write(path, aLines, ENCODING);
    }

    //For larger files

    void readLargerTextFile(String aFileName) throws IOException {
        System.out.print("***** readLargerTextFile *****\n");
        Path path = Paths.get(aFileName);
        Scanner scanner =  new Scanner(path, ENCODING.name());
        while (scanner.hasNextLine()){
            //process each line in some way
            log(scanner.nextLine());
        }
    }

    void readLargerTextFileAlternate(String aFileName) throws IOException {
        System.out.print("***** readLargerTextFileAlternate *****\n");
        Path path = Paths.get(aFileName);
        BufferedReader reader = Files.newBufferedReader(path, ENCODING);
        String line = null;
        while ((line = reader.readLine()) != null) {
            //process each line in some way
            log(line);
        }
    }

    void writeLargerTextFile(String aFileName, List<String> aLines) throws IOException {
        System.out.print("***** writeLargerTextFile *****\n");
        Path path = Paths.get(aFileName);
        BufferedWriter writer = Files.newBufferedWriter(path, ENCODING);
        for(String line : aLines){
            writer.write(line);
            writer.newLine();
        }
        writer.flush();
    }

    private static void log(Object aMsg){
        System.out.println(String.valueOf(aMsg));
    }

}

http://www.javapractices.com/topic/TopicAction.do?Id=42 

How to download and save a file from url using Java

Give a try to Java NIO:

try {
    URL url = new URL("http://portal.com/img/logo-header.gif");
    ReadableByteChannel rbc = Channels.newChannel(url.openStream());
    FileOutputStream fileOutputStream = new FileOutputStream("C:\\src\\a.gif");
    fileOutputStream.getChannel().transferFrom(rbc, 0, 1 << 24);
} catch (Exception ex) {
    ex.printStackTrace();
}

Using transferFrom() is potentially much more efficient than a simple loop that reads from the source channel and writes to this channel. Many operating systems can transfer bytes directly from the source channel into the filesystem cache without actually copying them.
http://docs.oracle.com/javase/6/docs/api/java/nio/channels/FileChannel.html