The main method

Learn main(String[] args) and printing with System.out.println.

What is the main method?

Every Java program starts from the main method. This method is the entry point: when the JVM runs, it calls main first.

Its signature is:

public static void main(String[] args)

Here public means accessibility, static means it is called at class level, void means it returns nothing. String[] args holds command-line parameters.

To print text to the screen you use System.out.println. It prints the output and moves the cursor to a new line.

println vs print

System.out.println moves the cursor to a new line after printing. System.out.print keeps it on the same line.

System.out.print("A");
System.out.print("B");
// Output: AB

System.out.println("A");
System.out.println("B");
// Output: A\nB

Use println for separate lines and print for same-line output. Which one you choose depends on the format you want.

Exercise Write your first Java program

Define a Main class with a main method. Inside main, print Hello with System.out.println.

Show example solution

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello");
    }
}

Test yourself

What parameter does main take?
- String[] args
- int x
- double[] data
- boolean flag
Show answer

String[] args — main takes a String array: the command-line parameters.

Complete the println call

System.out.____("Hello");

Show answer

System.out.println("Hello");

Match the keywords

public

Accessible
static

Class-level
void

No return
String[]

Parameter type

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