exchange/id fix the bugs

src/main/java/uk/ac/cf/spring/demo/takeaway/index/ExchangeController.java

+package uk.ac.cf.spring.demo.takeaway.index;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.servlet.ModelAndView;
+
+import java.util.List;
+
+@Controller
+public class ExchangeController {
+//    page /exchangeItemList
+    @GetMapping("/exchange")
+    public ModelAndView getExchange() {
+        ModelAndView modelAndView = new ModelAndView("/page/itemList");
+        ExchangeService exchangeService =ExchangeService.getInstance();
+        List<ExchangeItem> exchangeItems =exchangeService.getExchangeItems();
+        modelAndView.addObject("exchangeItems", exchangeItems);
+        return modelAndView;
+    }
+//    page /exchangeItemDetail
+    @GetMapping("/exchange/{id}")
+    public ModelAndView getExchangeItem(@PathVariable Long id) {
+        ModelAndView modelAndView = new ModelAndView("/page/itemDetail");
+        ExchangeService exchangeService = ExchangeService.getInstance();
+        ExchangeItem exchangeItem = exchangeService.getExchangeItem(id);
+        modelAndView.addObject("exchangeItem", exchangeItem);
+        return modelAndView;
+
+
+
+    }
+}

src/main/java/uk/ac/cf/spring/demo/takeaway/index/ExchangeService.java

@@ -23,6 +23,9 @@ public class ExchangeService {
         }
         return singleton;
     }
+    public List<ExchangeItem> getExchangeItems() {
+        return exchangeItems;
+    }
     // through id to search exchangeItem
     public ExchangeItem getExchangeItem(Long id) {
         return exchangeItems.stream().filter(exchangeItem ->