Complex Logic Patterns
Advanced Conditional Strategies in Java
Complex logic patterns enable developers to handle sophisticated decision-making scenarios with elegant and efficient code structures.
State Machine Implementation
public enum UserState {
PENDING, ACTIVE, BLOCKED, SUSPENDED
}
public class UserStateManager {
public static String handleUserTransition(UserState currentState, boolean isVerified) {
return switch (currentState) {
case PENDING -> isVerified ? "Activate" : "Remain Pending";
case ACTIVE -> isVerified ? "Continue" : "Suspend";
case BLOCKED -> "No Transition Allowed";
case SUSPENDED -> isVerified ? "Reactivate" : "Remain Suspended";
};
}
}
Conditional Logic Complexity Patterns
Pattern |
Description |
Use Case |
State Machine |
Manage complex state transitions |
User authentication |
Strategy Pattern |
Dynamic behavior selection |
Algorithm switching |
Chain of Responsibility |
Conditional processing pipeline |
Request handling |
Strategy Pattern Example
interface PaymentStrategy {
boolean processPayment(double amount);
}
class CreditCardPayment implements PaymentStrategy {
public boolean processPayment(double amount) {
// Credit card payment logic
return amount > 0;
}
}
class PayPalPayment implements PaymentStrategy {
public boolean processPayment(double amount) {
// PayPal payment logic
return amount > 0;
}
}
Conditional Processing Pipeline
graph TD
A[Input] --> B{First Condition}
B -->|True| C[Process Step 1]
B -->|False| D{Second Condition}
D -->|True| E[Process Step 2]
D -->|False| F[Default Handling]
Chain of Responsibility Pattern
abstract class Handler {
protected Handler nextHandler;
public void setNextHandler(Handler handler) {
this.nextHandler = handler;
}
public abstract boolean process(Request request);
}
class AuthenticationHandler extends Handler {
public boolean process(Request request) {
if (isAuthenticated(request)) {
return nextHandler != null
? nextHandler.process(request)
: true;
}
return false;
}
}
Complex Condition Composition
public class ComplexConditionDemo {
public static boolean advancedValidation(User user) {
return Optional.of(user)
.filter(u -> u.getAge() >= 18)
.filter(u -> u.hasValidCredentials())
.filter(u -> !u.isBlocked())
.isPresent();
}
}
Design Principles for Complex Logic
- Separate concerns
- Use composition over inheritance
- Implement clear state transitions
- Minimize side effects
- Use immutable objects
- Leverage functional interfaces
- Implement lazy evaluation
- Avoid excessive complexity
Advanced Condition Techniques
public class PredicateComposition {
public static Predicate<String> combinedValidation() {
Predicate<String> notNull = Objects::nonNull;
Predicate<String> notEmpty = s -> !s.isEmpty();
Predicate<String> validLength = s -> s.length() > 3;
return notNull.and(notEmpty).and(validLength);
}
}
By mastering these complex logic patterns, LabEx learners can create more robust, flexible, and maintainable Java applications with sophisticated conditional logic.