Java Programming Basics: A Guide for Beginners

Writing the First Java Program

It's now time to create our first learn Java program. Let's begin with the classic "Hello, World!" example:

Here's what's happening in this code:

public class HelloWorld: This line declares a class named "HelloWorld." Java programs are organized into classes, and each class has a name (which must match the filename).public static void main(String[] args): This line defines the main method. It's the entry point for our program. When we run our learn Java program, it starts executing from the main method.System.out.println("Hello, World!");: This line uses the System.out object to print the text "Hello, World!" to the console.To run your program:Save it with a .java extension. For example: Open the command prompt or terminalNavigate to the directory where the file is savedCompile the program by running javac Execute it with java HelloWorld

If all goes well, you'll see "Hello, World!" printed to your console.

Java Program Execution

Basic Java Concepts

Now that you've got your feet wet, let's explore some foundational Java concepts:

1. Variables and Data Types:

Variables are used to store data in a program. In Java, we must declare the data type of a variable before using it. The different data types used in are:

Primitive Data Types:

byte: A 1-byte data type used to store small numbers. It has a range of -128 to 127.short: A 2-byte data type used for larger numbers. It ranges from -32,768 to 32,767.int: A 4-byte data type used for storing integers. It ranges from -2,147,483,648 to 2,147,483,647.long: An 8-byte data type used for large integer values. It can hold values from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.float: A 4-byte data type used for storing floating-point numbers with single-precision. It is used for numbers with fractional parts.double: An 8-byte data type for double-precision floating-point numbers. It is commonly used for storing numbers with decimal points.boolean: Represents a true or false value, which is used for conditional expressions.char: A 2-byte data type that stores a single character, such as a letter, number, or symbol.

Reference Data Types (Object Data Types):

String: Used to represent a sequence of characters. Strings are objects and are widely used for text processing.Array: An object that stores a collection of elements of the same data type. Arrays can be of any data type, including other objects.Class: Represents a blueprint for creating objects. Custom classes can be defined to encapsulate data and behavior.Interface: Defines a contract for classes that implement it, specifying a set of methods that must be provided by those classes.Enumeration (enum): A special type used to define collections of constants. Enums are often used for defining a set of related values.Date: With millisecond precision, it represents a specific instant in time.Wrapper Classes: learn Java provides wrapper classes like Integer, Double, Boolean, etc., that wrap primitive data types to enable them to be treated as objects.User-Defined Objects: Besides the built-in reference data types, allows developers to create their own custom objects and data types by defining classes.

Example:

2. Keywords:

Keywords are reserved words in Java. It has predefined meanings and cannot be used as identifiers (such as variable names, class names, or method names) in our . These keywords are an integral part of the language's syntax. They are used to define the structure and behavior of Java programs. Below are the keywords in learn Java programming: