CODEWITHSUNDEEP
javajakarta-ee
Makuna
Makuna

Reputation: 598

Show stdout in file and in console (with System.setOut(new PrintStream(new File("output-file.txt"))

I want to save the stdout into a file. For this, I used
System.setOut(new PrintStream(new File("output-file.txt")));

Now, there is no output in the console. 

        try {
            System.setOut(new PrintStream(new File("output-file.txt")));
        } catch (Exception e) {
             e.printStackTrace();
        }

Is there any possibility to show the stdout in the console, although I use stdout to fill a file?

Upvotes: 2

Views: 1711

Answers (4)

Bermos
Bermos

Reputation: 1

You can make a new subclass of the PrintStream class and then override it's methods to write to a second Stream and then pass that to System.out as you've already one. Further reading & example implementation: https://books.google.ch/books?id=lbnjAwAAQBAJ&lpg=PA326&ots=j7OUeuXzIa&dq=java%20duplicate%20printstream&pg=PA326#v=onepage&q=java%20duplicate%20printstream&f=false

Upvotes: 0

TiiJ7
TiiJ7

Reputation: 3412

You could create a PrintWriter with an OutputStream that does both writes.

final OutputStream stdOut = System.out;
try {
    System.setOut(new PrintStream(new OutputStream() {
        private PrintStream ps = new PrintStream(new File("output-file.txt"));

        @Override
        public void write(int b) throws IOException {
            ps.write(b);
            stdOut.write(b);
        }

        @Override
        public void flush() throws IOException {
            super.flush();
            ps.flush();
            stdOut.flush();
        }

        @Override
        public void close() throws IOException {
            super.close();
            ps.close();
            // stdOut.close(); // Normally not done
        }
    }));
} catch (Exception e) {
    e.printStackTrace();
}

System.out.println("Hello, world!");

Upvotes: 3

Sunchezz
Sunchezz

Reputation: 778

I never tried it, but i guess if you subclass the default Printstream you are able to print to console and file by yourself.

Something like: 

class MyPrintStream extends printStream {

    private PrintStream secondPrinter;

    .....

    @Override 
    public void println(Object content) {
       super.println(content);
       secondPrinter.println(content);
    }
}

and maybe call it like this:

System.out = new MyPrintStream(myFile, System.out);

Upvotes: 1

Daniel B.
Daniel B.

Reputation: 2601

You can not use the systems OutputStream to write to 2 sources. It is a static variable and it can only have 1 value at a time.

You can try however, saving a reference to the consoles default OutputStream, and then changing the Systems OutputStream to your custom output stream, and write to both of them with a custom method.

Upvotes: 0

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