System.out.println in Java


System.out.println is a method in Java that prints a message to the standard output (typically the console) and appends a newline character. It's widely used to display messages, data, and the results of operations during the execution of a program. This method is essential for understanding the flow of your code and debugging potential issues.

Breaking Down System.out.println

System.out.println may seem like a simple method, but it's worth understanding its components to get a better grasp of how it works.

  • System  A built-in class in the java.lang package. It cannot be instantiated and provides access to standard input, output, and error streams, among other system-related functionalities.

  • out  A static member of the System class that represents the standard output stream. It's an instance of the PrintStream class, which is responsible for writing data to an output stream.

  • println  A method of the PrintStream class that writes a message to the output stream and appends a newline character. It's overloaded to handle various data types, such as integers, floating-point numbers, characters, strings, and even objects (by calling their toString() method).


Using System.out.println is straightforward. You can call it in your code with a value or an expression as a parameter, and it will print the result to the console.


Let's look at an example to understand its usage −

public class Main {
   public static void main(String[] args) {
      int a = 5;
      int b = 10;
      System.out.println("Hello, world!");
      System.out.println("The value of a is: " + a);
      System.out.println("The sum of a and b is: " + (a + b));


When you run the program, the output will be −

Hello, world!
The value of a is: 5
The sum of a and b is: 15


In the code above, we declare two integer variables, a and b, and assign them the values 5 and 10, respectively.

We then use System.out.println to −

  • Print a simple message, "Hello, world!".

  • Print the value of the variable a.

  • Print the sum of the variables a and b.

As you can see, System.out.println allows us to output various types of data, making it an indispensable tool for understanding our code's behavior.

Points to Remember

While System.out.println is a powerful tool for debugging, it's essential to remember that it's not suitable for all situations. In complex applications or when dealing with multi-threaded environments, using a logging framework (such as Log4j or SLF4J) is a more appropriate choice, as it provides greater control over log levels, output formats, and destinations.


System.out.println is a fundamental tool in Java, especially for beginners learning the language. It provides an easy way to output data to the console, which is invaluable for understanding program flow and debugging issues. As you advance in your Java journey, you'll find more sophisticated tools for logging and debugging, but System.out.println will always be a handy tool in your developer toolkit.

Updated on: 15-May-2023

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