Learn Java Java Syntax

Every Java program follows a fixed structure. Even a simple program has a class and a main method.

Java code execution always starts from the main method.

Note

The class name must match the file name. If the file name is Main.java, the class name must be Main.

In Java, everything is written inside a class.

A class is a blueprint that defines how an object will behave.

The main method is the entry point of every Java program.

Without the main method, the Java program will not run.

Real World Scenario

Think of the main method as a power switch. The program turns on only when this switch exists.

Each instruction in Java is called a statement. Every statement ends with a semicolon.

The semicolon tells Java that the instruction is complete.

Caution

Missing a semicolon is one of the most common beginner mistakes in Java.

Java treats uppercase and lowercase letters as different.

Both variables are different and stored separately.

Comments are used to explain code and are ignored by the compiler.

Comments make code easier to read and understand.

Java uses curly braces to define blocks of code.

Everything inside the braces belongs to that block.

Java ignores extra spaces and empty lines, but proper formatting improves readability.

Well formatted code is easier to maintain and debug.

Pro Tip

Always format your code neatly. Clean code reflects clear thinking.

Keywords are reserved words with predefined meanings in Java.

Examples include: class public static void int

These words cannot be used as variable names.

Stop

Using Java keywords as identifiers will cause compilation errors.

Syntax errors occur when Java rules are broken.

Common causes include: Missing semicolons Incorrect brackets Wrong capitalization Misspelled keywords

The compiler will show an error message pointing to the issue.

Goal Achieved

You now understand the basic syntax rules that every Java program follows.