CopyFile.java

// implement the C-lang binary 'cp' in Java
import java.io.FileInputStream;
import java.io.FileOutputStream;

import java.io.FileNotFoundException;
import java.io.IOException;

class CopyFile {
 public static void main(String[] args) {
 // character placeholder
 int i;

 // check command-line argument number
 if (args.length != 2) {
 System.out.println("Wrong number of arguments.");
 System.out.println("Usage: CopyFile <file_in> <file_out>");
 return;
 }

 // buffer the input file and write to output file
 // use the 'try' context manager
 try(FileInputStream aFileIn = new FileInputStream(args[0]);
 FileOutputStream aFileOut = new FileOutputStream(args[1])) {
 do {
 // possible to do in a single line without buffering
 // but that removes the extra -1 sanity check
 i = aFileIn.read();
 if (i != -1) aFileOut.write(i);
 } while (i != -1);
 } catch (IOException aExc) {
 System.out.println("I/O Error: " + aExc);
 }
 }
}