simplify controller method

spring-mvc-java/src/main/java/com/baeldung/annotations/CustomResponseController.java

@@ -24,30 +24,39 @@ public class CustomResponseController {
 
     @GetMapping("/age")
     public ResponseEntity<String> age(@RequestParam("yearOfBirth") int yearOfBirth) {
-        int currentYear = Year.now().getValue();
-
-        if (currentYear < yearOfBirth) {
+        if (isInFuture(yearOfBirth)) {
             return new ResponseEntity<>("Year of birth cannot be in the future", HttpStatus.BAD_REQUEST);
         }
 
-        int age = currentYear - yearOfBirth;
-
-        return new ResponseEntity<>("Your age is " + age, HttpStatus.OK);
+        return new ResponseEntity<>("Your age is " + calculateAge(yearOfBirth), HttpStatus.OK);
     }
-    
+
+    private int calculateAge(int yearOfBirth) {
+        return currentYear() - yearOfBirth;
+    }
+
+    private boolean isInFuture(int year) {
+        return currentYear() < year;
+    }
+
+    private int currentYear() {
+        return Year.now().getValue();
+    }
+
     @GetMapping("/customHeader")
     public ResponseEntity<String> customHeader() {
         HttpHeaders headers = new HttpHeaders();
         headers.add("Custom-Header", "foo");
-        
+
         return new ResponseEntity<>("Custom header set", headers, HttpStatus.OK);
     }
-    
+
     @GetMapping("/manual")
     public void manual(HttpServletResponse response) throws IOException {
         response.setHeader("Custom-Header", "foo");
         response.setStatus(200);
-        response.getWriter().println("Hello World!");
+        response.getWriter()
+            .println("Hello World!");
     }
 
 }