DI-LoggerExample-After

public interface Logger {
    void append(String message);
}

public final class ConsoleLogger implements Logger {
    @Override
    public void append(String message) {
        System.out.println(message);
    }
}

public final class AnyClass {
    private final Logger logger;
    public AnyClass(Logger logger) {
        this.logger = logger;
    }
    public void doSomething() {
        logger.append("I do something!");
    }
}

public final class Main {
    public static void main(String[] args) {
        final Logger logger = new ConsoleLogger();
        final AnyClass any = new AnyClass(logger);
        any.doSomething();
    }
}