I am convinced to convert my Spring Java field injection [@Autowired] to constructor injection (among other reasons, to facilitate mock unit testing)...
Is there a utility I can use to automatically do that Spring field to constructor injection conversion?
For example, IntelliJ IDEA has generation shortcuts for a lot of things (i.e: generate setters & getters for fields); I'm hoping there's something similar to that... This is particularly useful when it is tedious to do the conversion manually, because a class to be converted already has numerous field-injected fields.
Yes, it's now implemented in IntelliJ IDEA.
1) Place your cursor on one of the @Autowired annotation.
2) Hit Alt+Enter.
3) Select Create constructor
This is the quick fix related to the inspection "Field injection warning":
Spring Team recommends: "Always use constructor based dependency injection in your beans. Always use assertions for mandatory dependencies".
Field injection/NullPointerException example:
class MyComponent { @Inject MyCollaborator collaborator; public void myBusinessMethod() { collaborator.doSomething(); // -> NullPointerException } }Constructor injection should be used:
class MyComponent { private final MyCollaborator collaborator; @Inject public MyComponent(MyCollaborator collaborator) { Assert.notNull(collaborator, "MyCollaborator must not be null!"); this.collaborator = collaborator; } public void myBusinessMethod() { collaborator.doSomething(); // -> safe } }