Snippet

Constructor Dependency Injection

Constructor injection is the recommended way to handle dependencies in Spring. It ensures the object is always in a valid state and facilitates testing.

snippet.java

java

@RestController
public class CheckoutController {
    private final PaymentProcessor processor;
 
    public CheckoutController(PaymentProcessor processor) {
        this.processor = processor;
    }
}

spring

Breakdown

private final PaymentProcessor processor

The dependency is declared as final, ensuring it cannot be changed after initialization.

public CheckoutController(...)

The constructor where Spring automatically injects the required dependency bean.

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Constructor Dependency Injection

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