Added the final version of Alex's code.

UI/app/src/main/java/com/example/capstone/Signal.java

@@ -1,36 +0,0 @@
-package com.example.capstone;
-
-public class Signal {
-
-    private String power;
-    private String alarm;
-    private String motor;
-
-    public Signal() {
-    }
-
-    public String getPower() {
-        return power;
-    }
-
-    public void setPower(String power) {
-        this.power = power;
-    }
-
-    public String getAlarm() {
-        return alarm;
-    }
-
-    public void setAlarm(String alarm) {
-        this.alarm = alarm;
-    }
-
-    public String getMotor() {
-        return motor;
-    }
-
-    public void setMotor(String motor) {
-        this.motor = motor;
-    }
-}
-

UI/app/src/main/java/com/example/capstone/User.java

@@ -1,50 +0,0 @@
-package com.example.capstone;
-
-public class User {
-
-    private String Firstname;
-    private String Lastname;
-    private String phone;
-    private String email;
-
-    public User(String fn, String ln, String ph, String em) {
-        Firstname = fn;
-        Lastname = ln;
-        phone = ph;
-        email = em;
-
-    }
-
-    public String getFirstname() {
-        return Firstname;
-    }
-
-    public void setFirstname(String firstname) {
-        Firstname = firstname;
-    }
-
-    public String getLastname() {
-        return Lastname;
-    }
-
-    public void setLastname(String lastname) {
-        Lastname = lastname;
-    }
-
-    public String getPhone() {
-        return phone;
-    }
-
-    public void setPhone(String phone) {
-        this.phone = phone;
-    }
-
-    public String getEmail() {
-        return email;
-    }
-
-    public void setEmail(String email) {
-        this.email = email;
-    }
-
-}

UI/app/src/main/java/com/example/capstone/VThiefPictures.java

@@ -31,7 +31,6 @@ import java.util.ArrayList;
 
 public class VThiefPictures extends AppCompatActivity {
     FirebaseAuth fAuth;
-    private ImageView mImageView;
     private FirebaseStorage storage=FirebaseStorage.getInstance();
     ImageView img1, img2, img3;
     DatabaseReference reff;

UI/app/src/main/java/com/example/capstone/addDriver.java

@@ -1,68 +0,0 @@
-package com.example.capstone;
-
-import android.app.Dialog;
-import android.content.Context;
-import android.content.DialogInterface;
-import android.content.Intent;
-import android.os.Bundle;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.widget.EditText;
-
-import androidx.appcompat.app.AlertDialog;
-import androidx.appcompat.app.AppCompatDialogFragment;
-
-import com.google.firebase.auth.FirebaseAuth;
-import com.google.firebase.database.DatabaseReference;
-
-public class addDriver extends AppCompatDialogFragment {
-    private EditText fn, ln, ph, em;
-    private addDriverListener listener;
-    DatabaseReference reff;
-    @Override
-    public Dialog onCreateDialog(Bundle savedInstanceState) {
-        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
-        LayoutInflater inflater = getActivity().getLayoutInflater();
-        View view = inflater.inflate(R.layout.add_driver, null);
-
-        builder.setView(view).setTitle("Add Driver").setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
-            @Override
-            public void onClick(DialogInterface dialog, int which) {
-
-            }
-        })
-        .setPositiveButton("Add", new DialogInterface.OnClickListener() {
-            @Override
-            public void onClick(DialogInterface dialog, int which) {
-                String fns = fn.getText().toString();
-                String lns = ln.getText().toString();
-                String phs = ph.getText().toString();
-                String ems = fn.getText().toString();
-                listener.applyTexts(fns, lns, phs, ems);
-            }
-        });
-
-        fn = view.findViewById(R.id.fname);
-        ln = view.findViewById(R.id.lname);
-        ph = view.findViewById(R.id.phone);
-        em = view.findViewById(R.id.email);
-
-        return builder.create();
-    }
-
-    @Override
-    public void onAttach(Context context) {
-        super.onAttach(context);
-
-        try {
-            listener = (addDriverListener) context;
-        } catch (ClassCastException e) {
-            throw new ClassCastException(context.toString()+"must implement addDriverListener");
-        }
-    }
-
-    public interface addDriverListener{
-        void applyTexts(String fn, String ln, String ph, String em);
-    }
-
-}

UI/app/src/main/java/com/example/capstone/homepage.java

@@ -25,7 +25,6 @@ public class homepage extends AppCompatActivity {
     FirebaseAuth fAuth;
     private Button setting, poweron, alarmoff, apps;
     DatabaseReference reff;
-    Signal sig;
     int check = 0;
     int check2 = 0;
     private ImageView a, e;
@@ -46,11 +45,9 @@ public class homepage extends AppCompatActivity {
         e = findViewById(R.id.engine);
 
         reff = FirebaseDatabase.getInstance().getReference().child("signal");
-        sig = new Signal();
-        sig.setMotor("off");
-        sig.setPower("off");
-        sig.setAlarm("off");
-        reff.child("1").setValue(sig);
+        reff.child("1").child("power").setValue("off");
+        reff.child("1").child("motor").setValue("off");
+        reff.child("1").child("alarm").setValue("off");
 
         setting.setOnClickListener(new View.OnClickListener() {
             @Override
@@ -71,18 +68,17 @@ public class homepage extends AppCompatActivity {
             @Override
             public void onClick(View v) {
                 if(check == 0){
-                    sig.setPower("on");
+                    reff.child("1").child("power").setValue("on");
                     e.setImageResource(R.drawable.ic_power_on);
                     et.setText("ON");
                     check = 1;
                 } else {
-                    sig.setPower("off");
+                    reff.child("1").child("power").setValue("off");
                     e.setImageResource(R.drawable.ic_power_off);
                     et.setText("OFF");
                     check = 0;
 
                 }
-                reff.child("1").setValue(sig);
             }
         });
 
@@ -90,18 +86,17 @@ public class homepage extends AppCompatActivity {
             @Override
             public void onClick(View v) {
                 if(check2 == 0){
-                    sig.setAlarm("on");
+                    reff.child("1").child("alarm").setValue("on");
                     a.setImageResource(R.drawable.ic_alarm_on);
                     at.setText("ON");
                     check2 = 1;
                 } else {
-                    sig.setAlarm("off");
+                    reff.child("1").child("alarm").setValue("off");
                     a.setImageResource(R.drawable.ic_alarm_off);
                     at.setText("OFF");
                     check2 = 0;
 
                 }
-                reff.child("1").setValue(sig);
             }
         });