wrting integers as 4 bytes to file java

Question

I am writing a java program in which I have to write all integers to a file. To make it more efficient I just want to write int as only 4 bytes(which I think will be a binary file kind of thing, but I am not sure) and while reading back from the file I just want to read the integers directly(I do not want to read bytes and then convert them to integer). Is there a way to do that.

I want to write millions of integers to the file I want the method to be fast and efficient.

I am new to this so please put up with me.

Answer 1

Use the DataOutputStream class or a RandomAccessFile. Both provide methods for writing structured binary data, for example the "int as 4 bytes" you want.

Answer 2

 FileOutputStream fos = new FileOutputStream("numbers.dat");
 DataOutputStream dos = new DataOutputStream(fos);
 dos.writeInt(my_int);
 dos.flush();
 dos.close();

If you want to have the data buffered wrap the file stream in to a buffered stream as below:

FileOutputStream fos = new FileOutputStream("numbers.dat");
BufferedOutputStream bos = new BufferedOutputStream(fos);
dos = new DataOutputStream(bos);