Common Pitfalls

When transitioning from JavaScript to Java development, you'll encounter many common pitfalls and errors. Understanding these pitfalls can help you avoid common problems and improve code quality.

Object-Oriented Programming Pitfalls

1. Inheritance vs Composition

Pitfall: Overusing Inheritance

Pitfall: Forgetting to Call super()

2. Method Overriding Pitfalls

Pitfall: Method Signature Mismatch

Pitfall: Access Modifier Issues

3. Interface and Abstract Class Pitfalls

Pitfall: Default Method Conflicts

Concurrent Programming Pitfalls

1. Thread Safety Issues

Pitfall: Shared Mutable State

Pitfall: Deadlock

2. Concurrent Collection Pitfalls

Pitfall: ConcurrentModificationException

Memory Management Pitfalls

1. Memory Leaks

Pitfall: Static References

Pitfall: Event Listener Memory Leaks

Spring Framework Pitfalls

1. Dependency Injection Issues

Pitfall: Circular Dependencies

Pitfall: Prototype Bean in Singleton

2. Transaction Management Pitfalls

Pitfall: Self-Invocation

Performance Pitfalls

1. String Concatenation

2. Collection Performance

Summary

Common pitfalls in Java development include:

1. Object-Oriented Pitfalls: Overusing inheritance, forgetting super() calls, method signature mismatches
2. Concurrent Programming Pitfalls: Thread safety issues, deadlocks, concurrent modification
3. Memory Management Pitfalls: Memory leaks from static references, event listeners
4. Spring Framework Pitfalls: Circular dependencies, prototype beans in singletons, transaction issues
5. Performance Pitfalls: Inefficient string concatenation, poor collection usage

Understanding these pitfalls helps you write more robust and efficient Java code. As a JavaScript developer, many of these concepts have parallels in JavaScript, but Java's stricter typing and different memory model introduce additional considerations.

Best Practices

1. Prefer composition over inheritance
2. Always call super() in constructors
3. Use @Override annotation for method overriding
4. Use thread-safe collections and atomic operations
5. Avoid circular dependencies in Spring
6. Use StringBuilder for string concatenation in loops
7. Choose appropriate collection types for your use case

Exercises

1. Identify and fix inheritance issues in your code
2. Implement thread-safe counters and collections
3. Detect and resolve memory leaks
4. Fix Spring dependency injection issues
5. Optimize string and collection operations

Next Steps

In the next module, we'll explore Java idioms and best practices for writing clean, maintainable code.