System.out.println vs PrintWriter

Question

Is there a difference in using these two? When would you use one over the other?

System.out.println(result);

versus

PrintWriter out = new PrintWriter(System.out);
out.println(result);
out.flush();

Answer 1

I recommend using PrintWriter if you have to print more than 10^3 lines in one go.

I got this by running these snippets 3 times each for n=10^1 to 10^7 and then taking mean of there execution time.

class Sprint{
    public static void main(String[] args) {
        int n=10000000;
        for(int i=0;i<n;i++){
            System.out.println(i);
        }
    }
}

import java.io.*;
class Pprint{
    public static void main(String[] args) {
        PrintWriter out = new PrintWriter(System.out);
        int n=10000000;
        for(int i=0;i<n;i++){
            out.println(i);
        }
        out.flush();
    }
}

Answer 2

The main difference is that System.out is a PrintStream and the other one is a PrintWriter. Essentially, PrintStream should be used to write a stream of bytes, while PrintWriter should be used to write a stream of characters (and thus it deals with character encodings and such).

For most use cases, there is no difference.

Answer 3

System.out is instance of PrintStream

So your question narrows down to PrintStream vs PrintWriter

• All characters printed by a PrintStream are converted into bytes using the platform's default character encoding. (Syso writes out directly to system output/console)

• The PrintWriter class should be used in situations that require writing characters rather than bytes.