Now, DTO to Entity fixed

src/main/java/com/gmu/bookshare/model/ListingDto.java

@@ -13,7 +13,7 @@ import java.util.Date;
 @Setter
 public class ListingDto {
 
-    private static final SimpleDateFormat dateFormat
+    private final SimpleDateFormat dateFormat
             = new SimpleDateFormat("yyyy-MM-dd HH:mm");
 
     private Long id;

src/main/java/com/gmu/bookshare/web/BookshareApiController.java

@@ -69,7 +69,7 @@ public class BookshareApiController {
 
     private ListingEntity convertToEntity(ListingDto listingDto) throws ParseException {
         ListingEntity post = modelMapper.map(listingDto, ListingEntity.class);
-        post.setCreateDate(ListingDto.getCreateDateConverted());
+        post.setCreateDate(listingDto.getCreateDateConverted());
         return post;
     }
 }