Java syntax is similar to C and C++. It uses semicolons to end statements and curly braces {} to define blocks of code.
Printing output in Java is typically done using System.out.println() or System.out.print() methods.
public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } }
Java variables must be declared with a specific type. Common types include int, double, boolean, String, etc.
int age = 25; double price = 19.99; boolean isActive = true; String name = "John";
Java supports for, while, and do-while loops.
// For loop for (int i = 1; i <= 5; i++) { System.out.println(i); } // While loop int count = 1; while (count <= 5) { System.out.println(count); count++; } // Do-while loop int num = 1; do { System.out.println(num); num++; } while (num <= 5);
Functions in Java are called methods. They are defined within classes and can be static (class-level) or instance methods
public class MyClass { // Static method public static void sayHello() { System.out.println("Hello, World!"); } // Instance method public void greet(String name) { System.out.println("Hello, " + name); } public static void main(String[] args) { sayHello(); // Calling a static method MyClass obj = new MyClass(); obj.greet("John"); // Calling an instance method } }
Methods in Java can return values using the return keyword.
public class Calculator { public int add(int a, int b) { return a + b; } public static void main(String[] args) { Calculator calc = new Calculator(); int result = calc.add(5, 3); System.out.println("Sum: " + result); } }
Java arrays are fixed-size collections of elements of the same type. ArrayLists are dynamically resizable lists.
// Arrays int[] numbers = {1, 2, 3, 4, 5}; System.out.println("First number: " + numbers[0]); // ArrayLists import java.util.ArrayList; ArrayList<String> names = new ArrayList<>(); names.add("Alice"); names.add("Bob"); System.out.println("First name: " + names.get(0));