018a - LoginActivity Shell from GUI

This lesson creates a UI shell for login before deep Firebase work.

In this step we:

1. Create LoginActivity from Android Studio GUI (Empty Views Activity) in activities.
2. Mark it as Launcher Activity from the GUI wizard.
3. Build login screen fields and buttons (username, password, login, login with Google).
4. Temporarily skip real auth and auto-navigate to MenuActivity after a short delay.

We intentionally do not connect authentication yet.

Step 1 - Create LoginActivity from GUI

Step 2 - Manifest sanity check (single launcher)

Update AndroidManifest.xml Because previous steps may already have MenuActivity as launcher, verify there is only one MAIN/LAUNCHER entry (we can expect 2 and you’ll have to update this manually. main Menu’s entry the same as Main’s entry)

Target state:

• LoginActivity is launcher.
• MenuActivity is regular activity (no launcher intent-filter, and not exported).

Step 3 - Build initial login XML shell

Replace the content of app/src/main/res/layout/activity_login.xml with the below xml so you have:

• Username (or email) field
• Password field
• Remember me checkbox (for later SharedPreferences lesson)
• Login button
• Login with Google button

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/main"
    android:orientation="vertical"
    android:padding="24dp"
    android:gravity="center_horizontal">

    <TextView
        android:id="@+id/tVtitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="Login"
        android:textStyle="bold"
        android:textSize="28sp"
        android:layout_marginBottom="20dp" />

    <EditText
        android:id="@+id/eTemail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="User name / e-mail"
        android:inputType="textEmailAddress" />

    <EditText
        android:id="@+id/eTpass"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="12dp"
        android:hint="Password"
        android:inputType="textPassword" />

    <CheckBox
        android:id="@+id/cBstayconnect"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="Remember me" />

    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:onClick="onLoginClick"
        android:text="Login" />

    <Button
        android:id="@+id/btnGoogleSignIn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:onClick="onGoogleLoginClick"
        android:text="Login with Google" />

</LinearLayout>

3.1 Required cleanup: move UI texts to strings.xml

We consistently teach string resources, so students should not leave hardcoded texts in the final XML.

Each student should replace these hardcoded values with @string/... entries in strings.xml:

• "Login"
• "User name / e-mail"
• "Password"
• "Remember me"
• "Login with Google"

Do this as a small cleanup phase after the layout compiles.

Step 4 - Temporary delayed navigation to MenuActivity

Until Firebase auth is wired, use delayed launch to skip login logic.

Edit app/src/main/java/.../activities/LoginActivity.java. Below is a diff against the current GUI-generated file in C:\Users\3stra\AndroidStudioProjects\TicTacMenu:

 package com.example.tictacmenu.activities;
 
+import android.content.Intent;
+import android.content.SharedPreferences;
 import android.os.Bundle;
+import android.os.Handler;
+import android.os.Looper;
+import android.view.View;
+import android.widget.CheckBox;
+import android.widget.Toast;
 
 import androidx.activity.EdgeToEdge;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.graphics.Insets;
 import androidx.core.view.ViewCompat;
 import androidx.core.view.WindowInsetsCompat;
 
 import com.example.tictacmenu.R;
+import com.example.tictacmenu.shell.MenuActivity;
 
 public class LoginActivity extends AppCompatActivity {
+
+    private static final long LOGIN_SHELL_DELAY_MS = 4000;
+    private static final String PREFS_NAME = "PREFS_NAME";
+    private static final String KEY_STAY_CONNECT = "stayConnect";
+
+    private SharedPreferences settings;
+    private CheckBox cBstayconnect;
+    private final Handler handler = new Handler(Looper.getMainLooper());
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         EdgeToEdge.enable(this);
         setContentView(R.layout.activity_login);
         ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
             Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
             v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
             return insets;
         });
+
+        settings = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
+        cBstayconnect = findViewById(R.id.cBstayconnect);
+
+        // SharedPreferences demo: restore and save the "remember me" checkbox.
+        cBstayconnect.setChecked(settings.getBoolean(KEY_STAY_CONNECT, false));
+        cBstayconnect.setOnCheckedChangeListener((buttonView, isChecked) ->
+                settings.edit().putBoolean(KEY_STAY_CONNECT, isChecked).apply()
+        );
+
+        // Temporary bridge: skip login until Firebase auth lesson is implemented.
+        handler.postDelayed(() -> {
+            settings.edit().putBoolean(KEY_STAY_CONNECT, cBstayconnect.isChecked()).apply();
+            startActivity(new Intent(LoginActivity.this, MenuActivity.class));
+            finish();
+        }, LOGIN_SHELL_DELAY_MS);
     }
+
+    public void onLoginClick(View view) {
+        Toast.makeText(this, "Email/password auth is added in a later lesson", Toast.LENGTH_SHORT).show();
+    }
+
+    public void onGoogleLoginClick(View view) {
+        Toast.makeText(this, "Google sign-in is an advanced later phase", Toast.LENGTH_SHORT).show();
+    }
+
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        handler.removeCallbacksAndMessages(null);
+    }
 }

This same delayed-navigation technique will later be reused in a dedicated Splash activity that appears before LoginActivity.

Step 5 - Run validation

1. Build and run.
2. App opens to login screen.
3. After about 4 seconds, app navigates to MenuActivity.
4. No Firebase auth calls are required yet.

Scope boundaries for this lesson

Not included in 018a:

• Real email/password Firebase auth calls
• FBRef creation and reference initialization
• Writing authenticated user data to RTDB

Those belong to separate lessons:

• Backend setup: 018b Firebase project + RTDB + Email/Password setup
• Auth wiring + FBRef: planned later in the sequence document (193).

Deferred advanced topic: Google login

Google login is intentionally moved out of this lesson to a dedicated lesson so 018a stays focused on UI shell + navigation only.

TODO (moved):

• Google Sign-In wiring
• Firebase signInWithCredential(...) for Google provider
• SHA1 fingerprint generation and Firebase Console registration
• Emulator-specific Google Sign-In pitfalls (Developer_Error / code 10)

Use the dedicated lesson:

• 018d Google OAuth login + SHA1 setup (Android + Firebase)

Suggested commit split

1. 018a: create LoginActivity from GUI as launcher
2. 018a: add login shell XML (email/password/login/google)
3. 018a: add delayed auto-navigation to MenuActivity
4. (Separate lesson) 018d: wire Google sign-in + SHA1 setup