Unit 5: Arrays and ArrayLists

Arrays

• Array: A fixed-size data structure that stores elements of the same data type.
• Declaration: Create an array and specify its type and size.

  int[] numbers = new int[5];
  

• Initialization: Set values for array elements.

  numbers[0] = 1;
  numbers[1] = 2;
  

• Accessing Elements: Access elements by their index.

  int firstNumber = numbers[0];
  

ArrayLists

• ArrayList: A dynamic-size data structure that stores objects of a specified data type.
• Declaration and Initialization: Create an ArrayList and add elements.

  ArrayList<String> names = new ArrayList<>();
  names.add("Alice");
  names.add("Bob");
  

• Accessing Elements: Get elements by index or use iteration.

  String firstPerson = names.get(0);
  for (String name : names) {
      // Code to process each name
  }
  

Unit 6: Object-Oriented Programming

Classes and Objects

• Class: A blueprint for creating objects, defining attributes and methods.

  class Car {
      String make;
      int year;
      // Methods and constructors
  }
  

• Object: An instance of a class created using the new keyword.

  Car myCar = new Car();
  myCar.make = "Toyota";
  myCar.year = 2022;
  

Constructors

• Constructor: Special method to initialize objects when created.

  class Car {
      String make;
      int year;
  
      Car(String make, int year) {
          this.make = make;
          this.year = year;
      }
  }
  

Inheritance

• Inheritance: A mechanism where a subclass can inherit attributes and methods from a superclass.

  class Animal {
      void eat() {
          // Code for eating
      }
  }
  
  class Dog extends Animal {
      void bark() {
          // Code for barking
      }
  

Polymorphism

• Polymorphism: Allows objects of different classes to be treated as objects of a common superclass. It supports method overriding.

  class Animal {
      void makeSound() {
          // Default animal sound
      }
  }
  
  class Dog extends Animal {
      @Override
      void makeSound() {
          // Dog's sound
      }