readInt()

Here is a program that reads four integers, adds them up, and writes the sum (as characters) to the monitor. It expects a data file "intData.dat".

import java.io.*;
class ReadInts
{
 public static void main ( String[] args ) 
 {
   String fileName = "intData.dat" ;  long sum = 0;

   try
   {      
     DataInputStream instr = 
       new DataInputStream(
         new BufferedInputStream(
           new FileInputStream( fileName  ) ) );

     sum += instr.readInt();
     sum += instr.readInt();
     sum += instr.readInt();
     sum += instr.readInt();
     
     System.out.println( "The sum is: " + sum );
     instr.close();
   }
   catch ( IOException iox )
   {
     System.out.println("Problem reading " + fileName );
   }
 }
}

The method readInt() grabs four bytes from the input stream and returns them as an int. That value can be used in arithmetic without conversion. (No parseInt()'s in this program).

     out.writeInt(  0 );
     out.writeInt(  1 );
     out.writeInt(255 );
     out.writeInt( -1 );