Spring io @Autowired: The blank final field may not have been initialized

what I assume is a pretty basic question here-

There are several flavors of questions regarding this error, but none in the first 5 results that have the added nuance of Spring.

I have the beginnings of a REST-ful webapp written in spring. I am trying to connect it to a database.

I have an entity named Workspace and am trying to use the spring injection of a bean( correct terminology ?) to save an instance of the workspace entity

package com.parrit;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.Assert;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.parrit.models.Workspace;
import com.parrit.models.WorkspaceRepository;

@RestController
@RequestMapping("/workspace")
public class WorkspaceController {

@Autowired
private final WorkspaceRepository repository;

@RequestMapping(method = RequestMethod.POST)
void save( @RequestBody String workspaceHTML) {
Workspace ws = new Workspace();
ws.setHTML(workspaceHTML);
repository.save(ws);
}
}

My error is on the repository variable ```private final WorkspaceRepository repository```. The compiler is complaining that it may not be initialized and attempting to run the app yields the same result.

How do I get an instance of this repository object into my controller in order to do save operations on it?

Exactly, you have to provide a constructor that assigns the final field

private final WorkspaceRepository repository;

@Autowired
public WorkspaceController(WorkspaceRepository repository){
this.repository = repository;
}

And Spring will be able to figure out how to initialise the object and inject the repository via the constructor

Having `@Autowired` and final on a field are contradictory.

The latter says: this variable has one and only one value, and it's initialized at construction time.

The former says: Spring will construct the object, leaving this field as null (its default value). Then Spring will use reflection to initialize this field with a bean of type WorkspaceRepository.

If you want final fields autowired, use constructor injection, just like you would do if you did the injection by yourself:

@Autowired
public WorkspaceController(WorkspaceRepository repository) {
this.repository = repository;
}