Keskustelu: Ohjelmointikysymykset: Java ja tiedoston avaaminen

import java.util.Scanner;
import java.util.Formatter;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.io.File;

public class InOut {

    Scanner inp = null;
    Formatter outp = null;
    File inTied = new File("index.htm");
    File inOt = new File("inOt.txt");

    public static void main(String[] args) {
        InOut io = new InOut();
        io.run();
    }

    private void run() {
        openInput(inTied, inp);
        openOutput(inOt, outp);
        kopioi(inp, outp);
        inp.close();
        outp.close();
        // ***********************************
        openInput(inOt, inp);
        openOutput(inTied, outp);
        kopioi(inp, outp);
        inp.close();
        outp.close();
    }

    private void kopioi(Scanner inpti, Formatter outpti) {
        String line;
        int count = 0;
        while (inpti.hasNext()) {
            count++;
            line = inpti.nextLine();
            outpti.format("%s\n", line);
        }
        System.out.println("Kopioitu " + count + " tietuetta");
    }

    private void openInput(File inFile, Scanner inpti) {

        try {
            inpti = new Scanner(inFile); // ../src/InOut.java

        } catch (FileNotFoundException ex) {
            System.err.println("Error1=" + ex);
            System.exit(1);
        }
        System.out.println("Avattu input " + inFile.getAbsolutePath());
        inp = inpti;
    }

    private void openOutput(File f, Formatter fm) {

        try {
            f.createNewFile();
        } catch (IOException ex) {
            System.err.println("Error2=" + ex);
            System.exit(2);
        }
        try {
            fm = new Formatter(f);
        } catch (FileNotFoundException filesNotFoundException) {
            System.err.println("Error3= " + filesNotFoundException);
            System.exit(3);
        }
        System.out.println("Avattu output " + f.getAbsolutePath());
        outp = fm;
    }
}