console.writeline and System.out.println

Question

What exactly is the technical difference between console.writeline and System.out.println? I know that System.out.println writes to s

Answer 1

They're essentially the same, if your program is run from an interactive prompt and you haven't redirected stdin or stdout:

public class ConsoleTest {
    public static void main(String[] args) {
        System.out.println("Console is: " + System.console());
    }
}

results in:

$ java ConsoleTest
Console is: java.io.Console@2747ee05
$ java ConsoleTest 

The reason Console exists is to provide features that are useful in the specific case that you're being run from an interactive command line:

• secure password entry (hard to do cross-platform)
• synchronisation (multiple threads can prompt for input and Console will queue them up nicely, whereas if you used System.in/out then all of the prompts would appear simultaneously).

Notice above that redirecting even one of the streams results in System.console() returning null; another irritation is that there's often no Console object available when spawned from another program such as Eclipse or Maven.