Spring default behavior for lazy-init

Question

I am beginner to spring, ESP Inversion of control. I was puzzled understanding the difference between the following

 <bean id="demo" class="Demo" lazy-init="false"/>  <bean id="demo" class="Demo" lazy-init="true"/>  <bean id="demo" class="Demo" lazy-init="default"/> 

To my understanding : lazy-init=false creates the bean at the startup and lazy-init=true doesn't create a bean at the startup rather creates the bean upon request for a particular bean. Correct me here, If my interpretation is wrong.

what exactly the default behavior of lazy-init is? How would it instantiate?

Answer 1

The default behaviour is false:

By default, ApplicationContext implementations eagerly create and configure all singleton beans as part of the initialization process. Generally, this pre-instantiation is desirable, because errors in the configuration or surrounding environment are discovered immediately, as opposed to hours or even days later. When this behavior is not desirable, you can prevent pre-instantiation of a singleton bean by marking the bean definition as lazy-initialized. A lazy-initialized bean tells the IoC container to create a bean instance when it is first requested, rather than at startup.

I suggest reading up

Answer 2

For those coming here and are using Java config you can set the Bean to lazy-init using annotations like this:

In the configuration class:

@Configuration // @Lazy - For all Beans to load lazily public class AppConf {      @Bean     @Lazy     public Demo demo() {         return new Demo();     } } 

For component scanning and auto-wiring:

@Component @Lazy public class Demo {     ....     .... }  @Component public class B {      @Autowired     @Lazy // If this is not here, Demo will still get eagerly instantiated to satisfy this request.     private Demo demo;      .......  }