Question

Hello I have the following code:

int i=12345;
DataOutputStream dos=new DataOutputStream(new FileOutputStream("Raw.txt"));
dos.write(i);
dos.close();
System.out.println(new File("Raw.txt").length());

The file size is being reported as 1 byte. Why is it not 4 bytes when an integer is 4 bytes long?

Thanks

Answer 1

While the DataOutputStream.write method takes an int argument, it actually only writes the bottom 8 bits of that argument. So you actually wrote only one byte … and hence the file is one byte long.

If you want to write the entire int you should use the writeInt(int) method.

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The underlying reason for this strangeness is (I believe) that the write(int) method is defined to be consistent with OutputStream.write(int) which in turn defined to be consistent with InputStream.read(). InputStream.read() reads a byte and returns it as an int … with the value -1 used to indicate the end-of-stream condition.