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| Java Programming for Beginners: Chapter 2 - Getting Started with Java Programming |
In this chapter, we'll start writing our first Java program and explore the basics of variables, data types, and control flow structures.
Writing Your First Java Program
Let's begin by writing a simple "Hello, World!" program in Java:
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public class HelloWorld {
public static void main(String[] args)
{ System.out.println("Hello, World!"); }
}
This program consists of a single class named HelloWorld. Within this class, we have a main method, which is the entry point of our program. The System.out.println() statement is used to print the text "Hello, World!" to the console.
Variables
In Java, variables are containers for storing data values. Before using a variable, you need to declare its type and optionally initialize it with a value. For example:
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int age; // Declaration age = 25; // Initialization
Here, we declared a variable named age of type int and assigned it the value 25.
Data Types
Java supports several primitive data types, including int, double, boolean, char, and more. Each data type has a specific range of values it can store. For example:
int: Represents integer values (e.g., -10, 0, 42).
double: Represents floating-point numbers (e.g., 3.14, -0.5, 2.0).
boolean: Represents boolean values (true or false).
char: Represents single characters (e.g., 'A', 'b', '$').
Control Flow Structures
Control flow structures allow us to control the flow of execution in our programs. Common control flow structures in Java include:
if-else statements: Used for conditional execution.
for loops: Used for iterating over a sequence of elements.
while loops: Used for repeating a block of code while a condition is true.
switch statements: Used for executing different code blocks based on the value of a variable.
In the next chapter, we'll explore these control flow structures in more detail and learn how to use them effectively in our Java programs.