How to Implement Conditional Method Chaining in Java 8

Question

How can I implement conditional method chaining in Java 8?

public class User {
    private String name;
    private int age;

    public User setName(String name) {
        this.name = name;
        return this;
    }

    public User setAge(int age) {
        this.age = age;
        return this;
    }

    public void display() {
        System.out.println("Name: " + name + ", Age: " + age);
    }
}

Answer

Conditional method chaining in Java 8 allows you to create fluent APIs where methods can be called sequentially based on certain conditions. This enhances code readability and maintainability.

import java.util.Optional;

public class ConditionalChainingExample {
    private boolean isAdult;
    private String message;

    public ConditionalChainingExample setIsAdult(boolean isAdult) {
        this.isAdult = isAdult;
        return this;
    }

    public ConditionalChainingExample setMessage(String message) {
        this.message = message;
        return this;
    }

    public void printMessage() {
        Optional.of(message)
            .ifPresent(msg -> System.out.println(isAdult ? msg : "Not an adult"));
    }
}

// Usage
new ConditionalChainingExample()  
    .setIsAdult(true)  
    .setMessage("Welcome!")  
    .printMessage();   // Prints: Welcome!  

new ConditionalChainingExample()  
    .setIsAdult(false)  
    .setMessage("Welcome!")  
    .printMessage();   // Prints: Not an adult

Causes

Need for clean and readable code.
Desire to structure method calls based on certain criteria.
Improving the usability of APIs and objects.

Solutions

Implement method chaining by returning 'this' from methods.
Use optional conditions to vary method calls.
Apply a conditional check before executing methods.

Common Mistakes

Mistake: Not returning 'this' from chaining methods.

Solution: Ensure each method in the chain returns 'this' to allow subsequent method calls.

Mistake: Forgetting to check the condition before method call.

Solution: Utilize Optional or conditionals before executing methods.

Helpers

Conditional Method Chaining
Java 8
Fluent APIs
Method Chaining Best Practices
Java Method Chaining