IO.println()
Prints a value to the console and ends the line.
Available since: Java 25
Syntax
static void println(Object obj)Parameters
| Parameter | Type | Description |
|---|---|---|
| obj | Object | What to print: a string, a number, an object (via its toString()). Can be called without an argument to print an empty line. |
Return value
voidNothing.
Examples
Printing different values:
void main() {
IO.println("Hello, world!");
IO.println(42);
IO.println();
IO.println(List.of(1, 2, 3));
}Output:
Hello, world!
42
[1, 2, 3]Several values on one line — through concatenation:
void main() {
String name = "Anna";
int age = 30;
IO.println(name + " is " + age);
IO.println("Sum: " + (2 + 3));
}Output:
Anna is 30
Sum: 5Notes
The java.lang.IO class appeared in Java 25 together with compact source files (void main() without a class) and needs no import. Internally it writes to System.out, so older code and pre-Java 25 tutorials do the same with System.out.println().
The method takes exactly one argument. The parentheses in "Sum: " + (2 + 3) matter: without them you get "Sum: 23".
See also
- IO.print() — Prints a value to the console without ending the line.
- IO.readln() — Prints a prompt and reads a line typed by the user.
- System.out.println() — The classic way to print to the console: prints a value and ends the line.
In the tutorial
- Your first program — The parts of a Java program: the main method, statements, output with IO.println, comments and the classic form with public class Main.