Java read from and write to a binary stream

A. Write to a binary stream

Assume that you have the following data that you would like to write to a binary stream.
      char aChar = 'T';
      long aLong = 109876L;
      int aInt = 98;
      String aString = "Nice"; //4 chars

1. Create the ByteBuffer
In java, char is 2 bytes, long is 8 bytes, int is 4 bytes. For the above data, we need in total 22 bytes.

      ByteBuffer buffer = ByteBuffer.allocate(22);

2. Put the data to the ByteBuffer
      buffer.putChar(aChar);
      buffer.putLong(aLong);
      buffer.putInt(aInt);
      buffer.put(aString.getBytes());

3. Write to the OutputStream
The code here is an example of how to write to a FileOutputStream.

      FileOutputStream fos = new FileOutputStream("<fileName>");
      fos.write(buffer.array());

B. Read from a binary stream

The sample code shows how to read from the binary file created above.

1. Create/get the InputStream
      File theFile = new File("<fileName>");
      FileInputStream fis = new FileInputStream(theFile);

2. Read data into a byte array
      byte[] byteArray = new byte[(int)theFile.length()];
      fis.read(byteArray);

3. Get the data
      ByteBuffer buffer = ByteBuffer.wrap(byteArray);
      char aChar = buffer.getChar();
      long aLong = buffer.getLong();
      int aInt = buffer.getInt();
      String aString = "";
      for (int i=0; i<4; i++) {
            sString += buffer.getChar();
      }

References:
1. How to convert byte array or char array to string in Java
2. Java how to read a binary file prepared by a c program

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