なんか消えてたから戻しました

app/src/main/java/com/example/oplogy/CreateUUID.java

@@ -5,12 +5,12 @@ import java.util.List;
 
 public class CreateUUID {
 
-    public static int generateUUID(List<String> classIdList ){
+    public static int generateUUID(List<Integer> classIdList ){
         while (true){
-            String uuid = String.valueOf((int)(Math.random() * 1000000));
+            int uuid = (int) (Math.random() * 100000);
             boolean isDuplicate = false;
-            for(String classId : classIdList){
+            for(int classId : classIdList){
-                if(classId.equals(uuid)){
+                if(classId==uuid){
                     //重複があればフラグを立て、ループを抜ける
                     isDuplicate = true;
                     break;
@@ -19,10 +19,12 @@ public class CreateUUID {
             //重複がなければ生成したUUIDを返す
             if (!isDuplicate) {
                 //firestoreに挿入処理
+                InsertClassIdforFirebase insertClassIdforFirebase = new InsertClassIdforFirebase();
+                insertClassIdforFirebase.insertClassId(uuid);
                 //テスト用
-                uuid="100";
+                uuid=100;
-                return Integer.parseInt(uuid);
+                return uuid;
             }
         }
     }
-}
+}

app/src/main/java/com/example/oplogy/FirestoreReception_classIdDatabase.java

@@ -17,14 +17,14 @@ import java.util.List;
 import java.util.Map;
 public class FirestoreReception_classIdDatabase {
     private FirebaseFirestore db;
-    private List<String> classIdList= new ArrayList<>();
+    private List<Integer> classIdList= new ArrayList<>();
 
     public FirestoreReception_classIdDatabase() {
         db = FirebaseFirestore.getInstance();
     }
 
 
-    public List<String> getAllDocumentsFromClassIdDatabase() {
+    public List<Integer> getAllDocumentsFromClassIdDatabase() {
         db.collection("classId_Database")
                 .get()
                 .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@@ -34,7 +34,7 @@ public class FirestoreReception_classIdDatabase {
                             for (QueryDocumentSnapshot document : task.getResult()) {
                                 Log.d("結果", document.getId() + " => " + document.getData());
                                 //データをListに追加
-                                classIdList.add((String) document.get("classId"));
+                                classIdList.add(((Long) document.get("classId")).intValue());
                             }
                         } else {
                             Log.d("結果", "Error getting documents: ", task.getException());
@@ -45,7 +45,7 @@ public class FirestoreReception_classIdDatabase {
         return classIdList;
     }
 
-    public List<String> getClassIdList() {
+    public List<Integer> getClassIdList() {
         return classIdList;
     }
 }

app/src/main/java/com/example/oplogy/InsertClassIdforFirebase.java

@@ -0,0 +1,19 @@
+package com.example.oplogy;
+
+import com.google.firebase.firestore.FirebaseFirestore;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class InsertClassIdforFirebase {
+    public void insertClassId(int classId) {
+        FirebaseFirestore db = FirebaseFirestore.getInstance();
+
+        Map<String, Object> data = new HashMap<>();
+        data.put("classId", classId); // classId is inserted as a number
+
+        db.collection("classId_Database").add(data)
+                .addOnSuccessListener(documentReference -> System.out.println("DocumentSnapshot added with ID: " + documentReference.getId()))
+                .addOnFailureListener(e -> System.err.println("Error adding document: " + e));
+    }
+}

app/src/main/java/com/example/oplogy/MainActivity.java

@@ -162,7 +162,7 @@ public class MainActivity extends AppCompatActivity implements View.OnClickListe
     //UUIDを表示するかのダイアログ
     private void showUUIDYesNoDialog() {
         firestoreReception_classIdDatabase = new FirestoreReception_classIdDatabase();
-        List<String> classIdList = firestoreReception_classIdDatabase.getAllDocumentsFromClassIdDatabase();
+        List<Integer> classIdList = firestoreReception_classIdDatabase.getAllDocumentsFromClassIdDatabase();
 
 
         AlertDialog.Builder builder = new AlertDialog.Builder(this);