Core Java

Strategy Pattern with CDI and lambdas

The strategy design pattern dynamically chooses an implementation algorithm, a strategy, at runtime. The pattern can be used to select different business algorithms depending on the circumstances.

We could define different algorithm implementations as separate classes. Or we make use of Java SE 8 lambdas and functions, that serve as lightweight strategy implementation here.

CDI is capable of injecting parameterized types:

public class Greeter {

    Function<String, String> greetingStrategy;

    public String greet(String name) {
        return greetingStrategy.apply(name);

A CDI producer creates and exposes the greeting depending on the dynamic logic. The actual strategy is represented by the Function type and being selected dynamically:

public class GreetingStrategyExposer {

    private final Function<String, String> formalGreeting = name -> "Dear " + name;
    private final Function<String, String> informalGreeting = name -> "Hey " + name;

    public Function<String, String> exposeStrategy() {
        // select a strategy
        return strategy;
Published on Java Code Geeks with permission by Sebastian Daschner, partner at our JCG program. See the original article here: Strategy Pattern with CDI and lambdas

Opinions expressed by Java Code Geeks contributors are their own.

Sebastian Daschner

Sebastian Daschner is a self-employed Java consultant and trainer. He is the author of the book 'Architecting Modern Java EE Applications'. Sebastian is a Java Champion, Oracle Developer Champion and JavaOne Rockstar.
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Back to top button