What is the difference between these two java statements?

Question

I've been learning java programming recently and I am quite confused between these two statements.

System.out.println("Hello, world");
System.console().printf("Hello, world");

I know that out is a static variable of System class and printf() is the method of Printstream class.

But I am not getting the second statement. I know a little bit of OOP . So if System class has a method like console() then how can a method have methods like printf() ?

Answer 1

The console() method doesn't have a method like printf() , it returns an object that has a printf() method. Specifically, the console() method returns a Console object.

This pattern is called method chaining .

Answer 2

So if System class has a method like console() then how can a method have methods like printf() ?

System.console() returns a Console object, and you're invoking the printf() method on that Console object.

Answer 3

The console() method returns an instance of Console object.

You can rewrite it like this:

Console console = System.console();
console.printf("Hello, world");

See https://docs.oracle.com/javase/7/docs/api/java/io/Console.html for more details

Answer 4

From System javadoc :

console()
Returns the unique Console object associated with the current Java virtual machine, if any.

So console() method returns a Console object and printf() is a method of class Console

System.out.println() on the other hand is calling println() method on the static PrintStream field "out" of class System

Answer 5

Java statements and method calls are evaluated left to right. System has a method console() which grants access to the console associate with the JVM. You are now working the object representing the console of the JVM when you call the method printf(). printf() is a method of the console of the JVM, not System itself.