Controller with error

src/main/java/ch/progetto152/Controller.java

@@ -0,0 +1,56 @@
+package ch.progetto152;
+
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/users")
+public class Controller {
+
+    @Autowired
+    private UserService userService;
+
+    @GetMapping
+    public ResponseEntity<List<User>> getAllUsers() {
+        List<User> users = userService.getAllUsers();
+        return new ResponseEntity<>(users, HttpStatus.OK);
+    }
+
+    @GetMapping("/{id}")
+    public ResponseEntity<User> getUserById(@PathVariable("id") Long id) {
+        User user = userService.getUserById(id);
+        if (user != null) {
+            return new ResponseEntity<>(user, HttpStatus.OK);
+        } else {
+            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
+        }
+    }
+
+    @PostMapping
+    public ResponseEntity<User> createUser(@RequestBody User user) {
+        User createdUser = userService.createUser(user);
+        return new ResponseEntity<>(createdUser, HttpStatus.CREATED);
+    }
+
+    @PutMapping("/{id}")
+    public ResponseEntity<User> updateUser(@PathVariable("id") Long id, @RequestBody User user) {
+        User updatedUser = userService.updateUser(id, user);
+        if (updatedUser != null) {
+            return new ResponseEntity<>(updatedUser, HttpStatus.OK);
+        } else {
+            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
+        }
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteUser(@PathVariable("id") Long id) {
+        boolean deleted = userService.deleteUser(id);
+        if (deleted) {
+            return new ResponseEntity<>(HttpStatus.NO_CONTENT);
+        } else {
+            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
+        }
+    }
+}