Object-Oriented Programming_ Core Java Concepts and Practices_Unit 1_Part 1.pptx
- 1. Object-Oriented Programming Dr. Tarun Kumar Vashishth
- 2. Agenda 01 Introduction to Object-Oriented Programming 02 OOP in Java: Implementation 03 Java Environment and Setup 04 Java Source File Structure 05 Java Compilation Process 06 Practical Examples and Best Practices
- 4. The Paradigm Shift OOP represents a paradigm shift from procedural programming, organizing code around "objects" rather than actions. This approach leverages concepts such as encapsulation, inheritance, and polymorphism to create modular, reusable, and maintainable code; it promotes a more intuitive alignment between code and real-world entities. Key Features of OOP OOP emphasizes modularity, reusability, and maintainability; these principles revolve around objects, classes, abstraction, encapsulation, inheritance, and polymorphism. Each object is an instance of a class, bundling data (attributes) and behavior (methods) together. Benefits of Using OOP OOP simplifies software development, encourages code reuse, and models real-world scenarios more effectively; leading to systems that are easier to understand, modify, and extend. Therefore it enhances collaboration and reduces development time and costs. What is Object-Oriented Programming?
- 5. 02 Abstraction Abstraction simplifies complex systems by modeling classes based on essential traits; hiding unnecessary details from the user. Thus, allowing developers to focus on what an object does rather than how it achieves its behavior. 01 Objects and Classes An object is a self-contained entity with attributes and behaviors, which is an instance of a class, thus a blueprint defining the structure and behavior of objects. Therefore objects interact with each other by invoking methods, enabling a dynamic and modular design. 03 Encapsulation Encapsulation bundles data and methods that operate on that data within a class; protecting data from external access or modification. It ensures data integrity by allowing access only through well- defined interfaces; promoting loose coupling and modular design. 04 Inheritance Inheritance enables a class to inherit properties and behaviors from another class, promoting code reuse and establishing hierarchical relationships. This mechanism allows for creating specialized classes from more general ones. 05 Polymorphism Polymorphism allows objects of different classes to be treated as objects of a common type, enabling flexibility and extensibility. This is achieved through method overriding and interfaces, allowing for dynamic method dispatch and generic programming. Core Concepts of OOP
- 6. OOP in Java: Implementation 02
- 7. 01 02 03 Java is inherently object- oriented, designed to support OOP principles from the ground up; by providing constructs for classes, objects, inheritance, and polymorphism natively. Therefore ensuring that developers can easily implement OOP designs. Java OOP Foundation In Java, a class is defined using the `class` keyword, with objects created via the `new` keyword. Attributes are declared as fields; methods define the behavior of objects, illustrating the fundamental building blocks of OOP in Java. Classes and Objects in Java Java supports inheritance through the `extends` keyword, allowing a class to inherit from a single superclass. Interfaces supports multiple inheritance of type; promoting code reuse and establishing hierarchical relationships between classes. Implementing Inheritance Java and Object-Oriented Principles
- 8. Abstraction and Encapsulation in Java Achieving Abstraction Abstraction in Java can be achieved using abstract classes and interfaces; where abstract classes may contain both abstract and concrete methods, while interfaces define a contract for classes to implement. Therefore focusing on essential characteristics of objects. Implementing Encapsulation Encapsulation is achieved through access modifiers such as `private`, `protected`, and `public`; where `private` restricts access to within the class, `protected` allows access within the class and subclasses, and `public` allows access from anywhere. Thus protecting data integrity and hiding complex implementation details.
- 9. 02 01 03 Method Overriding Method overriding occurs when a subclass provides a specific implementation for a method that is already defined in its superclass; enabling dynamic method dispatch based on the object's actual type. Thus ensuring that the correct method is called at runtime. Interface and Polymorphism Interfaces define a set of methods that a class must implement, allowing objects of different classes to be treated as objects of a common type. This enables polymorphism and promotes loose coupling between classes. Example: Polymorphic Behavior Consider a scenario with different shapes (Circle, Rectangle) implementing a common interface (Shape); where each shape provides its own implementation of the `draw()` method. Polymorphism allows you to treat these shapes uniformly. Polymorphism in Java
- 10. Java Environment and Setup 03
- 11. Configure environment variables such as `JAVA_HOME` and `PATH` to ensure that the system can locate the JDK tools; where `JAVA_HOME` points to the JDK installation directory, and `PATH` includes the JDK's `bin` directory. Thus allowing command-line tools like `javac` and `java` to be accessible from anywhere. Configuring the Environment The Java Development Kit (JDK) is essential for Java development, providing tools and libraries for compiling, debugging, and running Java programs. It includes the Java Runtime Environment (JRE), compiler (javac), and other utilities; required for developing applications. What is the JDK? Installing the JDK involves downloading the appropriate version for your operating system from the Oracle website or an open-source distribution like OpenJDK. After downloading, follow the installation instructions, and set the necessary environment variables. Installing the JDK Java Development Kit (JDK)
- 12. 01 02 03 Popular Java IDEs Popular Java IDEs include Eclipse, IntelliJ IDEA, and NetBeans, offer features such as code completion, debugging, and build automation. Thus enhancing developer productivity Setting Up an IDE To set up an IDE, download and install your preferred IDE, then configure it to use the installed JDK; where you may need to specify the JDK path in the IDE settings. Thus ensuring that the IDE can compile and run Java programs using the correct JDK version. Project Configuration IDEs use project-based organization, so create a new Java project within your IDE, setting the project’s structure and dependencies; then you can add source files, libraries, and configure build settings as needed. This provides a structured environment. Integrated Development Environments (IDEs)
- 13. Java Source File Structure 04
- 14. Package Declaration Java source files typically start with a package declaration, specifying the package to which the class belongs; where the `package` keyword is used to define the package, which helps organize classes into logical groups. Thus preventing naming conflicts and providing a namespace. Import Statements Import statements allow you to use classes from other packages without specifying their fully qualified names, which use the `import` keyword to include classes from other packages. Thus simplifying code and reducing verbosity. Class Definition The main part of a Java file is the class definition, defining the structure and behavior of objects, by using the `class` keyword to define a class, which includes fields (attributes) and methods (behaviors). Thus creating instances of the class. Anatomy of a Java File
- 15. Fields represent the state of an object, declared as variables within the class; where each field has a data type and a name, and can be accessed and modified using appropriate access modifiers. Thus defining the object’s properties. Fields (Attributes) Methods define the behavior of an object, declared as functions within the class; where each method has a return type, name, and a list of parameters. They perform operations on the object's data and interact with other objects. Methods (Behaviors) Constructors are special methods used to initialize objects when they are created; where they have the same name as the class and no return type, which are invoked using the `new` keyword. Thus setting initial values for the object’s fields. Constructors Components of a Java Class
- 16. 03 01 02 Follow naming conventions, use meaningful names, and provide comments to improve code readability; writing clean and maintainable code is essential for effective Java development. Thus ensuring that your code will be easily understandable. Best Practices A typical Java source file includes a package declaration, import statements, and a class definition, followed by fields, methods, and constructors; such file is starts with package declaration, uses import statements for external classes, and then defines a class with attributes and behaviors. Thus demonstrating how Java source files are organized. Sample Code Structure The provided code demonstrates how to define a class with fields, methods, and constructors, illustrating how to implement OOP principles in Java. Hence it shows how to create objects and manipulate their state. Code Explanation Example Java Source File
- 18. From Source Code to Bytecode Java source code (.java files) is compiled into bytecode (.class files) by the Java compiler (javac); where bytecode is platform-independent and can be executed on any system with a Java Virtual Machine (JVM). Therefore enabling Java’s "write once, run anywhere" capability. Role of the Java Compiler (javac) The Java compiler (javac) checks the syntax and semantics of the source code, generates bytecode, and reports errors; ensuring that the code is valid and conforms to the Java language specifications Bytecode Verification Before execution, the JVM verifies the bytecode to ensure that it is safe and does not violate any security constraints, which prevents malicious or erroneous code from causing harm to the system. Thus maintaining the integrity and security of Java applications. Overview of Compilation
- 19. Using the javac Command To compile a Java source file, use the `javac` command followed by the file name, for example: `javac MyClass.java`; and the compiler generates a `.class` file with the bytecode for each class defined in the source file. Therefore creating executable code. Handling Compilation Errors If the compiler encounters errors, it will report them with line numbers and descriptions, such as syntax errors, type mismatches, or missing classes, so you must correct the errors in the source code and recompile. Thus ensuring that the code is free of errors before running it. Classpath and Package Resolution The compiler uses the classpath to locate classes and packages, which can be specified using the `-classpath` or `- cp` option, which allows the compiler to find external libraries and dependencies needed for compilation. Thus properly configuring the classpath is crucial for successful compilation. Compilation Steps
- 20. The Java Virtual Machine (JVM) executes bytecode, by loading `.class` files, verifying bytecode, and interpreting or compiling it into machine code for execution. Thus providing a platform- independent runtime Java Virtual Machine (JVM) To run a Java program, use the `java` command followed by the name of the class containing the `main` method, for example: `java MyClass`, so the JVM loads and executes the specified class. Executing Bytecode The Java Runtime Environment (JRE) provides the necessary libraries and tools for running Java programs, includes the JVM and core Java libraries allowing users to run Java applications without the need for Java Runtime Environment (JRE) Running Java Programs
- 21. Practical Examples and Best Practices 06
- 22. Real-World Examples of OOP in Java A banking system can be modeled using OOP concepts, with classes such as Account, Customer, and Transaction; where Account encapsulates account details and operations, Customer stores customer information, and Transaction records financial transactions. Case Study 1: Banking System An e-commerce application can be structured using OOP, with classes such as Product, Cart, and Order; where Product represents items for sale, Cart manages items in a shopping cart, and Order handles order processing, thus illustrating how OOP can be used to design modular applications. Case Study 2: E-commerce Application A library management system can utilize OOP principles with classes like Book, Member, and Loan; where Book stores book details and availability, Member tracks member information, and Loan manages book loans and returns. Thus showcasing OOP in managing information. Case Study 3: Library Management System
- 23. 01 02 03 Ensures that a class has only one instance and provides a global point of access to it, useful for managing resources or configurations; and it controls instance creation. Singleton Pattern Provides an interface for creating objects without specifying their concrete classes, delegating object creation to subclasses; it is flexible and extensible. Factory Pattern Defines a one-to-many dependency between objects, so that when one object changes state, all its dependents are notified and updated automatically; it enables loose coupling. Observer Pattern Common OOP Design Patterns in Java
- 24. Leverage inheritance, composition, and polymorphism to reuse code and reduce redundancy; designing modular classes with well-defined interfaces is key to effective code reuse. Code Reusability Write clean, well-documented code with clear separation of concerns to improve maintainability; following coding standards and using design patterns simplifies future modifications and extensions. Maintainability Design your application with scalability in mind, considering factors such as database access, concurrency, and distributed computing; where using appropriate data structures and algorithms is key to high scalability. Scalability Best Practices for OOP in Java