Spring - Inject Instance Of Class with Only Static Members

Question

I have a class Foo in package com.example.dao -

@Component
public class Foo {
    public static final String nameAbc = "Abc";
    public static final String nameDef = "Def";
    public static List<String> getNames() {
        return ImmutableList.of(nameAbc, nameDef);
    }

    // I created this for testing purpose.
    // I was testing if maybe Spring needs an instance of class to inject.
    public static Foo instance = new Foo();
}

In a Configuration BeanConfig class I wish to inject a List<Foo> and perform some operator on it -

@Configuration
public class BeanConfig {

    private List<Foo> foos;

    @Autowired
    public void setFoos(List<Foo> foos) {this.foos = foos;}

    @Bean
    public Bar bar() {
        // using foos in some logic here for creating Bar bean
    }
}

I have also tried using @ComponentScan on BeanConfig class -

@ComponentScan(basePackages = "com.example.dao")

but class Foo is still not injected as I get an empty list. What exactly is the mistake here?

Update - It came out to be a different issue - some beans in com.example.dao package did not had default constructors which caused @ComponentScan to throw an exception while creating their instances. Updating the constructors resolved the issue.

Answer 1

I used Spring Boot to test your code. Please check your configuration
2016-12-21 20:45:36.326 INFO 25224 --- [ main] com.mycompany.app.Application : Started Application in 11.997 seconds (JVM running for 12.861)

Result: [Abc, Def]

@Configuration
@ComponentScan
@EnableAutoConfiguration
public class Application {
    @Autowired
    private Environment env;

    private static final Logger LOGGER = LoggerFactory.getLogger(Application.class);

    @PostConstruct
    public void initApplication() throws IOException {
        LOGGER.info("Running with Spring profile(s) : {}", env.getActiveProfiles());
    }

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);

        List<String> list = Foo.getNames();
        System.out.println(list);
    }    
} 

Answer 2

It came out to be a different issue - some beans in com.example.dao package did not had default constructors which caused @ComponentScan to throw an exception while creating their instances. Updating the constructors resolved the issue.