diff --git a/src/main/java/org/ntlab/amaryllis/server/entities/Account.java b/src/main/java/org/ntlab/amaryllis/server/entities/Account.java
index 424e4e9..3791906 100644
--- a/src/main/java/org/ntlab/amaryllis/server/entities/Account.java
+++ b/src/main/java/org/ntlab/amaryllis/server/entities/Account.java
@@ -4,6 +4,8 @@
 import org.ntlab.amaryllis.server.models.Accounts;
 
 import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.Set;
 import java.util.UUID;
 
 public class Account {
@@ -14,8 +16,8 @@
     @JsonIgnore
     private String password;
     private String introduction;
-    private ArrayList<String> followings;
-    private ArrayList<String> followers;
+    private HashSet<String> followings;
+    private HashSet<String> followers;
     private ArrayList<String> contributions;
     private ArrayList<String> history;
 
@@ -23,8 +25,8 @@
         this.name = name;
         this.password = password;
         this.uid = UUID.randomUUID().toString();
-        followings = new ArrayList<>();
-        followers = new ArrayList<>();
+        followings = new HashSet<>();
+        followers = new HashSet<>();
         history = new ArrayList<>();
         contributions = new ArrayList<>();
         introduction = "";
@@ -52,11 +54,11 @@
         return contributions;
     }
 
-    public ArrayList<String> getFollowers() {
+    public HashSet<String> getFollowers() {
         return followers;
     }
 
-    public ArrayList<String> getFollowings() {
+    public HashSet<String> getFollowings() {
         return followings;
     }
 
@@ -76,4 +78,14 @@
         this.token = token;
     }
 
+    public void setName(String name) {
+        this.name = name;
+    }
+    public void setPassword(String password){
+        this.password=password;
+    }
+
+    public void setIntroduction(String introduction) {
+        this.introduction = introduction;
+    }
 }