diff --git a/app/src/main/java/com/example/tampopo_client/models/Activity.java b/app/src/main/java/com/example/tampopo_client/models/Activity.java
index 7c3d626..6dcf984 100644
--- a/app/src/main/java/com/example/tampopo_client/models/Activity.java
+++ b/app/src/main/java/com/example/tampopo_client/models/Activity.java
@@ -13,6 +13,9 @@
         this.updateTime = updateTime;
     }
 
+    public Activity() {
+    }
+
     public String getUserId() {
         return userId;
     }