Fix the prolem with using system.in/out for read/write objects in by file [closed]

问题

This is a method with System.in and System.out using for write and read some object

    PrintStream out = new PrintStream(System.out);
    Transit.outputTransport(Parking, out);
    System.out.println(Parking.toString());
    out.close();

    InputStream in = new BufferedInputStream(System.in);
    Transport forOutNew = Transit.inputTransport(in);
    System.out.println(forOutNew.toString());
    in.close();

Every time, System.out.println(forOutNew.toString()); prints null . How can I fix the problem?

Given below is the original code which I changed to the one mentioned above:

    OutputStream os = new FileOutputStream("out.txt");
    Transit.outputTransport(Parking, os); - byte string of object information to file
    os.close();
    InputStream is = new FileInputStream("out.txt");
    System.out.println(Parking.toString());
    Transport forOut = Transit.inputTransport(is); - read byte string and create new object in method
    is.close();
    System.out.println(forOut.toString());
    System.out.println();

Transit methods

public static void outputTransport (Transport v, OutputStream out)  { 
    try (DataOutputStream output = new DataOutputStream(out))
    {
        if (v instanceof Cars){
            output.write(0);
        } else if (v instanceof Motos){
            output.write(1);
        } else {
            throw new IOException();
        }
        output.write(((v.getType()).getBytes()).length);
        output.write((v.getType()).getBytes());
        output.write(v.getNumber());
        String[] mas2 = v.getAllModels();
        double[] mas1 = v.getAllPrices();
        for (int i=0; i < v.getNumber(); i++)
        {
            output.writeDouble(mas1[i]);
            output.writeInt(((mas2[i]).getBytes()).length);
            output.write((mas2[i]).getBytes());
        }
        System.out.println();
        System.out.println("Successful");
    }
    catch(IOException e){
        System.out.println(e.getMessage());
    }
}

public static Transport inputTransport (InputStream in) { // input stream
    try (DataInputStream input = new DataInputStream(in)) {
        int flag = input.readByte();
        if ((flag == 0) || (flag == 1)) { // cars = 0, motos = 1
            int n = input.readByte();
            int b;
            String s = new String(input.readNBytes(n));
            if (flag == 0) {
                n = input.readByte();
                Factory newObject = new CreatorFactory(flag, s, n);
                Transport forOut = newObject.createTransport();
                for (int i = 0; i < n; i++) {
                    forOut.changePrice("default"+i, input.readDouble());
                    b = input.readInt();
                    s = new String(input.readNBytes(b));
                    forOut.changeModel("default"+i, s);
                }
                return forOut;
            } else if (flag == 1) {
                Factory newObject = new CreatorFactory(flag, s);
                Transport forOut = newObject.createTransport();
                n = input.readByte();
                for (int i = 0; i < n; i++) {
                    forOut.addModel("default", input.readDouble());
                    b = input.readInt();
                    s = new String(input.readNBytes(b));
                    forOut.changeModel("default", s);
                }
                return forOut;
            }
        } else {
            throw new IOException();
        }
    }
    catch(IOException | NoSuchModelNameException | DuplicateModelNameException e){
        System.out.println(e.getMessage());
    }
    return null;
}

来源：https://stackoverflow.com/questions/60098656/fix-the-prolem-with-using-system-in-out-for-read-write-objects-in-by-file

标签

java

file

object

system