diff --git a/app/src/androidTest/java/com/example/childguard/Bluetooth_device_save.java b/app/src/androidTest/java/com/example/childguard/Bluetooth_device_save.java
new file mode 100644
index 0000000..de0df1c
--- /dev/null
+++ b/app/src/androidTest/java/com/example/childguard/Bluetooth_device_save.java
@@ -0,0 +1,21 @@
+package com.example.childguard;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+public class Bluetooth_device_save extends AppCompatActivity {
+    final SharedPreferences pref= PreferenceManager.getDefaultSharedPreferences(this);
+    public Bluetooth_device_save() {
+    }
+    public void device_save(String deviceAddress){
+        SharedPreferences.Editor e=pref.edit();
+        e.putString("bluetooth_device1",deviceAddress);
+        e.apply();
+    }
+    public String device_info(){
+        return pref.getString("bluetooth_device1","not_device");
+    }
+}