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Java Programming

Write better, more maintainable Java code with proven best practices and design patterns.

What's Covered​

This section focuses on Java best practices that make a real difference in your code quality. Learn the principles that separate good Java code from great Java code.

Topics​

Java Variable Types and Best Practices​

Comprehensive guide to understanding Java variable types, best practices, and modern features.

You'll learn:

  • Interface vs Concrete Types

    • When to use List vs ArrayList
    • Benefits of programming to interfaces
    • Flexibility and testability

  • Primitives vs Wrapper Classes

    • int vs Integer decision guide
    • Performance implications and autoboxing pitfalls
    • Handling null values correctly

  • Modern Java Features

    • var for local variables (Java 10+)
    • Records for data classes (Java 14+)
    • Text blocks and pattern matching
    • Switch expressions

  • Real-World Examples

    • DAO pattern implementations
    • Configuration classes
    • Method parameter best practices
    • Collection type selection strategies

Read Variable Types and Best Practices Guide →

Why These Practices Matter​

Code Maintainability​

  • Easier to refactor and extend
  • Change implementations without breaking clients
  • More readable and self-documenting

Performance​

  • Primitives are faster than wrappers
  • Reduced memory usage
  • Better JVM optimization

Team Collaboration​

  • Consistent code style
  • Industry-standard patterns
  • Clear intent and purpose

Philosophy​

These guides follow the principle that good code is:

  • Simple - Easy to understand
  • Maintainable - Easy to modify
  • Correct - Does what it should
  • Efficient - Performs well

Getting Started​

Java Beginners​

Start with understanding:

  1. Basic syntax and OOP concepts
  2. Collections framework
  3. Variable types guide (this section)

Experienced Developers​

Use this as:

  • Quick reference for best practices
  • Code review checklist
  • Team coding standards

Common Mistakes to Avoid​

Programming to Implementation​

ArrayList<String> names = new ArrayList<>();  // Too specific

Programming to Interface​

List<String> names = new ArrayList<>();  // Flexible

Using Wrappers for Simple Values​

Integer count = 0;  // Unnecessary overhead
for (int i = 0; i < 1000; i++) {
    count++;  // Boxing/unboxing on every iteration!
}

Using Primitives​

int count = 0;  // Fast and efficient
for (int i = 0; i < 1000; i++) {
    count++;
}

Using == for Wrapper Comparison​

Integer a = 200;
Integer b = 200;
if (a == b) { }  // May be false! (caching)

Using equals()​

Integer a = 200;
Integer b = 200;
if (a.equals(b)) { }  // Always correct

Learning Resources​

Books​

  • Effective Java by Joshua Bloch
  • Clean Code by Robert Martin
  • Java Concurrency in Practice by Brian Goetz

Practice​

  • Code reviews with these guidelines
  • Refactor existing code
  • Build sample projects applying these patterns

Next Steps​

After mastering these basics, explore:

  • Design Patterns - GOF patterns in Java
  • Concurrency - Thread-safe programming
  • JUnit Testing - Write testable code (see Build Tools section)
  • Gradle - Build automation (see Build Tools section)
  • Spring Framework - Enterprise Java