Read from and write to a file in java (1): java.nio.file.Files

The Files class was introduced in Java 7. It contains only static methods that are convenient to use for operations on a file.

A. Read from a file

          Path theFile = FileSystems.getDefault().getPath("<dirctory>", "<file name>");

1. the readAllLines method
           List<String> allLines = Files.readAllLines(theFile);

2. the newBufferedReader
            BufferedReader reader = Files.newBufferedReader(theFile);
            String line = "";
            for ((line = reader.readLine()) != null) {
                      System.out.println(line);
           }

3. the lines method
          Stream<String> lineStream = Files.lines(theFile);
          List<String> lineList = lineStream.collect(Collectors.toList());

4. the readAllBytes method
          byte[] allByes = Files.readAllBytes(theFile);

5. the newInputStream method
          InputStream is = Files.newInputStream(theFile);
          byte[] isBytes = new byte[Files.size(theFile)];
          is.read(isBytes); //read the file to the byte array

6. the newByteChannel method
          //The advantage of using SeekableByteChannel is that it allows you
          //to set an arbitrary position to start reading and writing
          SeekableByteChannel sbc = Files.newByteChannel(theFile);
          String encode = System.getProperty("file.encoding");
          ByteBuffer theBuffer = ByteBuffer.allocate(theFile.toFile().length());
          sbc.read(theBuffer);
          theBuffer.reWind();
          String theString = CharSet.forName(encode).decode(theBuffer).toString();

B. Write to a file

          Path theFile = FileSystems.getDefault().getPath("<dirctory>", "<file name>");

1. the newBufferedWriter method
          BufferedWriter writer = Files.newBufferedWriter(theFile);
          PrintWriter pw = new PrintWriter(writer);

2. the newOutputStream method
          OutputStream os = Files.newOutputStream(theFile);

3. the write method
          byte[] theBytes = (new String("The words to write")).getBytes();
          Files.write(theFile, theBytes);

4. the newByteChannel method
          SeekableByteChannel sbc = Files.newByteChannel(theFile);
          byte[] theBytes = (new String("The words to write")).getBytes();
          ByteBuffer theBuffer = ByteBuffer.wrap(theBytes);
          sbc.write(theBuffer);

                              > Next

References:

1. Read from and write to a file in Java (2): Other commonly used methods
2. Read from and write to the command line in Java
3. Java communications over network
4. Class Files

---------------------------------------------------------------------------------------------------------------

                        
If you have ever asked yourself these questions, this is the book for you. What is the meaning of life? Why do people suffer? What is in control of my life? Why is life the way it is? How can I stop suffering and be happy? How can I have a successful life? How can I have a life I like to have? How can I be the person I like to be? How can I be wiser and smarter? How can I have good and harmonious relations with others? Why do people meditate to achieve enlightenment? What is the true meaning of spiritual practice? Why all beings are one? Read the book free here.