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     lt bean id  demo  class  Demo  lazy-init  false   gt    lt bean id  demo  class  Demo  lazy-init  true   gt    lt bean id  demo  class  Demo  lazy-init  default   gt    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

User · Answer

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;

    .......
 }

User · Answer

When we use lazy-init  default  as an attribute in  element  the container picks up the value specified by default-lazy-init  true false  attribute of  element and uses it as lazy-init  true false     If default-lazy-init attribute is not present in  element than lazy-init  default  in  element will behave as if lazy-init- false

User · Answer

lazy-init is the attribute of bean  The values of lazy-init can be true and false  If lazy-init is true  then that bean will be initialized when a request is made to bean  This bean will not be initialized when the spring container is initialized  and  if lazy-init is false then the bean will be initialized with the spring container initialization

User · Answer

The lazy-init  default  setting on a bean only refers to what is set by the default-lazy-init attribute of the enclosing beans element  The implicit default value of default-lazy-init is false   If there is no lazy-init attribute specified on a bean  it s always eagerly instantiated

User · Answer

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

[spring] Spring default behavior for lazy-init

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