04 System.out.println() | Core Java | Murari Walake

In Java, System.out.println() is a method used to print a line of text or a value to the standard output, which is typically the console or terminal window where the program is running. It is a part of the System class, which provides access to the standard input, output, and error streams.

The System.out is an instance of the PrintStream class, which represents the standard output stream. By calling the println() method on System.out, you can print text or values followed by a new line character ("\n") to move the cursor to the next line.

Here's the general syntax of System.out.println():

System.out.println(expression);

The expression can be a string, a variable, a constant, or any valid Java expression that evaluates to a printable value. For example:

System.out.println("Hello, world!"); // Prints a string

int num = 10;
System.out.println(num); // Prints the value of the variable 'num'

double pi = 3.14159;
System.out.println("The value of pi is: " + pi); // Prints a string concatenated with a variable value

The println() method automatically converts the given expression to its string representation and prints it to the console. It then moves the cursor to the next line, so the subsequent output appears on a new line.

Alternatively, if you want to print without moving to the next line, you can use System.out.print() instead of System.out.println(). For example:

System.out.print("Hello, ");
System.out.print("world!");
This code will output "Hello, world!" without a line break between the two parts.

Remember that System.out.println() is mainly used for debugging purposes or providing information to the user during program execution.