Reading x bytes at a time from a file in java

Question

I want to read x bytes at a time from a file, (say "testFile.raw"), and output those bytes to another file.

For example:

read 20 bytes from testFile.raw -> dump into outputfile.jpg
...repeat until done...

Is this possible?

Answer 1

Here is an example using a byte array of size 20 :

    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.InputStream;
    import java.io.OutputStream;

    public class FileInputOutputExample {

        public static void main(String[] args) throws Exception {

            try{
                    byte[] b = new byte[20];
                    InputStream is = new FileInputStream("in.txt");
                    OutputStream os = new FileOutputStream("out.txt");

                    int readBytes = 0;

                    while ((readBytes  = is.read(b)) != -1) {
                      os.write(b, 0, readBytes);
                    }
                    is.close();
                    os.close();

            }catch(IOException ioe){
                System.out.println("Error "+ioe.getMessage());
            }
         }
     }