📚 Week 4

🔧 Introduction to Maven

Understanding Maven

• What is Maven?
  • Maven is a build automation and project management tool for Java projects.
  • It simplifies the build process, dependency management, and project structure.

Basic Operations

• Creating a Maven Project:

  • Use an IDE to create a new Maven project.
  • Define the project's groupId, artifactId, and version in the pom.xml file.

• Managing Dependencies:

  • Declare project dependencies in the pom.xml file.
  • Maven automatically downloads and manages the required libraries.

• Building the Project:

  • Use Maven commands like mvn compile, mvn test, and mvn package to build the project.

🚀 Practical Exercise: Building a Maven Project

• Task: Create a simple Maven project and explore its structure and build process.
• Instructions:
  • Create a new Maven project using your IDE
  • Define a simple Java class.
  • Build the project using Maven commands and observe the generated artifacts.

💡 Discussion

• Discuss the benefits of using Maven for Java project management and build automation.
• Explore how Maven simplifies dependency management and promotes a standardized project structure.

📊 JSON and GSON Library

Understanding JSON

• What is JSON?
  • JSON (JavaScript Object Notation) is a lightweight data interchange format.
  • It is easy for humans to read and write and easy for machines to parse and generate.

Basic Operations with GSON

• Adding GSON Dependency:

  • Include the GSON library dependency in your project's pom.xml file.

• Object to JSON Conversion:

  Gson gson = new Gson();
  String json = gson.toJson(object);

• JSON to Object Conversion:

  Gson gson = new Gson();
  Object object = gson.fromJson(json, Object.class);

• Reading from a JSON File:

  Gson gson = new Gson();
  BufferedReader reader = new BufferedReader(new FileReader("file.json"));
  Object object = gson.fromJson(reader, Object.class);

🗺️ Practical Exercise: JSON Serialization and Deserialization

• Task: Use the GSON library to convert Java objects to JSON and vice versa.
• Instructions:
  • Create a Java class with a few fields and methods.
  • Use GSON to convert an instance of the class to a JSON string.
  • Write the JSON string to a file.
  • Read the JSON file and deserialize it back into a Java object.

💡 Discussion

• Discuss the importance of JSON as a data interchange format in modern web development.
• Explore how libraries like GSON simplify working with JSON in Java applications.

🧪 Introduction to Unit Testing and JUnit 5

Understanding Unit Testing

• What is Unit Testing?
  • Unit testing is a software testing method that focuses on testing individual units or components of code.
  • It helps ensure the correctness and reliability of individual parts of the application.

JUnit 5 Basics

• Adding JUnit 5 Dependency:

  • Include the JUnit 5 dependency in your project's pom.xml file.

• Writing a Test Case:

  import org.junit.jupiter.api.Test;
  import static org.junit.jupiter.api.Assertions.*;
  
  class ExampleTest {
      @Test
      void testMethod() {
          // Test case logic here
          assertEquals(expected, actual);
      }
  }

• Running Tests:

  • Use an IDE or Maven command mvn test to run the test cases.

Test-Driven Development (TDD)

• What is TDD?
  • TDD is a software development approach where tests are written before the actual code.
  • It follows a cycle of writing a failing test, writing minimal code to pass the test, and refactoring the code.

🧩 Practical Exercise: Testing a Java Class

• Task: Write unit tests for a Java class using JUnit 5.
• Instructions:
  • Create a Java class with a few methods that perform specific operations.
  • Write unit tests for each method using JUnit 5 assertions.
  • Run the tests and ensure they pass.
  • Optionally, practice TDD by writing tests before implementing the methods.

💡 Discussion

• Discuss the benefits of unit testing in ensuring code quality and reducing bugs.
• Explore how TDD can lead to more reliable and maintainable code.

🚨 Exception Handling

Understanding Exceptions

• What are Exceptions?
  • Exceptions are events that occur during the execution of a program, disrupting the normal flow of instructions.
  • They are used to handle errors or exceptional conditions gracefully.

Types of Exceptions

• Checked Exceptions:

  • Checked exceptions are checked at compile-time and must be explicitly handled or declared in the method signature.
  • Examples: IOException, SQLException.

• Unchecked Exceptions:

  • Unchecked exceptions are not checked at compile-time and do not need to be explicitly handled.
  • Examples: NullPointerException, ArrayIndexOutOfBoundsException.

Handling Exceptions

• Try-Catch Block:

  try {
      // Code that may throw an exception
  } catch (ExceptionType e) {
      // Exception handling code
  }

• Throwing Exceptions:

  if (condition) {
      throw new ExceptionType("Exception message");
  }

🎯 Practical Exercise: Handling Exceptions

• Task: Implement exception handling in a Java program.
• Instructions:
  • Create a Java class with a method that may throw an exception.
  • Use a try-catch block to handle the exception gracefully.
  • Throw a custom exception in a specific scenario.

💡 Discussion

• Discuss the importance of exception handling in creating robust and reliable software.
• Explore best practices for handling exceptions and designing exception hierarchies.

🧪🚨 Unit Testing with Exceptions

Testing Exceptions

• Asserting Exceptions with JUnit 5:

  import org.junit.jupiter.api.Test;
  import static org.junit.jupiter.api.Assertions.*;
  
  class ExceptionTest {
      @Test
      void testExceptionThrown() {
          assertThrows(ExceptionType.class, () -> {
              // Code that throws the exception
          });
      }
  }

🎯 Practical Exercise: Testing Exception Scenarios

• Task: Write unit tests to verify exception handling in a Java class.
• Instructions:
  • Create a Java class with methods that throw exceptions in specific scenarios.
  • Write unit tests using JUnit 5 to assert that the expected exceptions are thrown.
  • Ensure that the exceptions are handled correctly in the class.

💡 Discussion

• Discuss the importance of testing exception scenarios to ensure the robustness of the application.
• Explore strategies for designing effective exception handling tests.