@Scope for bean scope in Spring Boot - Step-by-Step Execution

Concept Flow - @Scope for bean scope

Define Bean with @Scope

↓

Spring Container creates Bean

↓

Check Scope Type

↓

Singleton

↓

One instance

↓

Bean injected/used

Spring reads @Scope on a bean, decides how many instances to create, then injects the bean accordingly.

Execution Sample

Spring Boot

@Bean
@Scope("prototype")
public MyBean myBean() {
  return new MyBean();
}

Defines a bean with prototype scope so Spring creates a new instance each time it is requested.

Execution Table

Step	Action	Scope Check	Bean Instance Created	Instance Count
1	Spring starts and reads bean definition	prototype	No	0
2	First request for bean	prototype	Yes	1
3	Second request for bean	prototype	Yes	2
4	Third request for bean	prototype	Yes	3
5	No more requests	-	No	3

💡 No more requests for the bean, prototype scope creates new instance each time

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
instanceCount	0	1	2	3	3

Key Moments - 2 Insights

Why does Spring create a new bean instance each time with prototype scope?

Because the execution_table shows at each request (steps 2,3,4) a new instance is created, matching prototype behavior.

What happens if the scope is singleton instead?

Spring creates only one instance at startup and reuses it, so instanceCount would stay 1 after first creation.

Visual Quiz - 3 Questions

Look at the execution_table, how many bean instances exist after the second request?

A 1

B 2

C 3

D 0

💡 Hint

Check the 'Instance Count' column at step 3 in execution_table

At which step does Spring decide not to create a new bean instance?

A Step 5

B Step 2

C Step 1

D Step 4

💡 Hint

Look for 'Bean Instance Created' = 'No' in execution_table

If the scope was singleton, how would the instanceCount change after multiple requests?

A Increase by 1 each request

B Reset to 0 after each request

C Stay at 1 after first request

D Increase only on odd requests

💡 Hint

Refer to key_moments explanation about singleton scope behavior

Concept Snapshot

@Scope annotation sets bean lifecycle.
Singleton: one instance per container.
Prototype: new instance per request.
Spring creates or reuses bean based on scope.
Use @Scope("prototype") for multiple instances.
Default is singleton scope.

Full Transcript

The @Scope annotation in Spring Boot controls how many instances of a bean Spring creates and manages. When a bean is marked with @Scope("prototype"), Spring creates a new instance every time the bean is requested. This contrasts with the default singleton scope, where Spring creates one instance and reuses it. The execution table shows Spring starting with zero instances, then creating a new one on each request for prototype scope. The variable tracker counts how many instances exist after each request. Key moments clarify why prototype scope creates new instances and how singleton scope differs. The visual quiz tests understanding of instance counts and scope behavior. Remember, @Scope controls bean lifecycle and instance creation in Spring.