added a ViewPager2 to switch between page fragments

added a PagerAdapter (FragmentStateAdapter) to provide the fragments for the ViewPager2
added the necessary fragments
added the necessary listeners for the TabLayout and the ViewPager2

.gitignore

@@ -15,7 +15,8 @@ gen/
                             
 # Local configuration file (sdk path, etc)
 local.properties
-                        
+mqtt.properties
+
 # Windows thumbnail db
 Thumbs.db
                 

app/build.gradle.kts

@@ -1,8 +1,14 @@
+import java.io.FileInputStream
+import java.util.Properties
+
 plugins {
     id("com.android.application")
     id("org.jetbrains.kotlin.android")
 }
 
+val mqttProperties = Properties()
+mqttProperties.load(FileInputStream(rootProject.file("mqtt.properties")))
+
 android {
     namespace = "de.chrissthecoder.store"
     compileSdk = 34
@@ -13,6 +19,11 @@ android {
         targetSdk = 34
         versionCode = 1
         versionName = "1.0"
+
+        buildConfigField("String", "MQTT_USERNAME", mqttProperties.getProperty("username"))
+        buildConfigField("String", "MQTT_PASSWORD", mqttProperties.getProperty("password"))
+        buildConfigField("String", "MQTT_HOST", mqttProperties.getProperty("host"))
+        buildConfigField("String", "MQTT_PORT", mqttProperties.getProperty("port"))
     }
 
     buildTypes {
@@ -36,6 +47,7 @@ android {
 
     buildFeatures {
         viewBinding = true
+        buildConfig = true
     }
 }
 
@@ -48,4 +60,5 @@ dependencies {
     implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:2.7.0")
     implementation("androidx.navigation:navigation-fragment-ktx:2.7.7")
     implementation("androidx.navigation:navigation-ui-ktx:2.7.7")
+    implementation("org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.5")
 }

app/src/main/AndroidManifest.xml

@@ -1,14 +1,14 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools">
+          xmlns:tools="http://schemas.android.com/tools">
+    <uses-permission android:name="android.permission.INTERNET" />
 
-    <application
+    <application android:icon="@mipmap/ic_launcher"
-        android:icon="@mipmap/ic_launcher"
+                 android:label="@string/app_name"
-        android:label="@string/app_name"
+                 android:roundIcon="@mipmap/ic_launcher_round"
-        android:roundIcon="@mipmap/ic_launcher_round"
+                 android:supportsRtl="true"
-        android:supportsRtl="true"
+                 android:theme="@style/Theme.Store"
-        android:theme="@style/Theme.Store"
+                 tools:targetApi="31">
-        tools:targetApi="31">
         <activity
             android:name=".MainActivity"
             android:exported="true"
@@ -16,10 +16,8 @@
             android:theme="@style/Theme.Store.NoActionBar">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
-
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
     </application>
-
 </manifest>

app/src/main/java/de/chrissthecoder/store/MainActivity.kt

@@ -37,7 +37,7 @@ class MainActivity : AppCompatActivity() {
         // menu should be considered as top level destinations.
         appBarConfiguration = AppBarConfiguration(
             setOf(
-                R.id.nav_home, R.id.nav_gallery, R.id.nav_slideshow
+                R.id.nav_dashboard, R.id.nav_gallery, R.id.nav_slideshow
             ), drawerLayout
         )
         setupActionBarWithNavController(navController, appBarConfiguration)

app/src/main/java/de/chrissthecoder/store/adapter/DashboardFragmentPagerAdapter.kt

@@ -0,0 +1,20 @@
+package de.chrissthecoder.store.adapter
+
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.FragmentManager
+import androidx.lifecycle.Lifecycle
+import androidx.viewpager2.adapter.FragmentStateAdapter
+import de.chrissthecoder.store.ui.dashboard.tabfragment.ShoppinglistFragment
+import de.chrissthecoder.store.ui.dashboard.tabfragment.UnderstockFragment
+
+class DashboardFragmentPagerAdapter(manager: FragmentManager, lifecycle: Lifecycle) : FragmentStateAdapter(manager, lifecycle) {
+
+    override fun getItemCount() : Int {
+        return 2
+    }
+
+    override fun createFragment(position: Int) : Fragment {
+        return  if(position == 0)   { ShoppinglistFragment() }
+                else                { UnderstockFragment() }
+    }
+}

app/src/main/java/de/chrissthecoder/store/mqtt/MqttHandler.kt

@@ -0,0 +1,118 @@
+package de.chrissthecoder.store.mqtt
+
+import android.util.Log
+import de.chrissthecoder.store.BuildConfig
+import org.eclipse.paho.client.mqttv3.*
+
+class MqttHandler {
+
+    companion object {
+        private const val LINE = "_________________________"
+
+        private const val CONNECTION_TIMEOUT = 3
+        private const val CONNECTION_KEEP_ALIVE_INTERVAL = 60
+        private const val CONNECTION_CLEAN_SESSION = true
+        private const val CONNECTION_RECONNECT = true
+    }
+
+    private val client: MqttClient
+
+    init {
+        Log.d(this.javaClass.name, "Enter Initializer")
+
+        val clientId: String = "Test Smartphone"
+
+        val serverURL = "tcp://" + BuildConfig.MQTT_HOST + ":" + BuildConfig.MQTT_PORT
+        client = MqttClient(serverURL, clientId, null)
+
+        Log.d(this.javaClass.name, "Set Mqtt Call-Back and Connect")
+
+        client.setCallback(object : MqttCallbackExtended {
+            override fun connectionLost(cause: Throwable?) {
+                Log.w(this.javaClass.name, "Connection Lost")
+            }
+
+            override fun messageArrived(topic: String?, message: MqttMessage?) {
+                Log.d(this.javaClass.name, "Message on Topic: \"" + topic + "\" Arrived")
+                val payload = message?.payload?.toString(Charsets.UTF_8)
+            }
+
+            override fun deliveryComplete(token: IMqttDeliveryToken?) {
+                Log.d(this.javaClass.name, "Message successful delivered")
+            }
+
+            override fun connectComplete(reconnect: Boolean, serverURI: String?) {
+                var message = "Successful "
+                if (reconnect) { message += "re" }
+                message += "connected to: "
+                serverURI?.let { Log.d(this.javaClass.name,  message + it) }
+            }
+        })
+
+        Log.d(this.javaClass.name, "MQTT Credentials:")
+        Log.d(this.javaClass.name, LINE)
+        Log.d(this.javaClass.name, "Client ID: " + clientId)
+        Log.d(this.javaClass.name, "Server URL: " + serverURL)
+        Log.d(this.javaClass.name, "Username: " + BuildConfig.MQTT_USERNAME)
+        Log.d(this.javaClass.name, "Password: " + BuildConfig.MQTT_PASSWORD)
+        Log.d(this.javaClass.name, LINE)
+
+        connect()
+    }
+
+    private fun connect() {
+        try {
+            Log.d(this.javaClass.name, "Connecting to Broker...")
+
+            // Set up the connection options
+            val mqttConnectOptions = MqttConnectOptions()
+            mqttConnectOptions.isAutomaticReconnect = CONNECTION_RECONNECT
+            mqttConnectOptions.isCleanSession = CONNECTION_CLEAN_SESSION
+            mqttConnectOptions.userName = BuildConfig.MQTT_USERNAME
+            mqttConnectOptions.password = BuildConfig.MQTT_PASSWORD.toCharArray()
+            mqttConnectOptions.connectionTimeout = CONNECTION_TIMEOUT
+            mqttConnectOptions.keepAliveInterval = CONNECTION_KEEP_ALIVE_INTERVAL
+
+            client.connect(mqttConnectOptions)
+        } catch (ex: MqttException) {
+            handleConnectionFailure(ex)
+        }
+    }
+
+    private fun handleConnectionFailure(cause: Throwable?) {
+        Log.w(this.javaClass.name,"Failed to connect: ${Log.getStackTraceString(cause)}")
+    }
+
+    fun subscribe(topic: String, qos: Int = 0) {
+        try {
+            Log.d(this.javaClass.name, "Subscribe to Topic: $topic")
+            client.subscribe(topic, qos)
+        } catch (ex: MqttException) {
+            Log.e(this.javaClass.name,"Error on subscribing to Topic: $topic", ex)
+        }
+    }
+
+    fun publish(topic: String, msg: String, qos: Int = 0, retained: Boolean = false) {
+        try {
+            val mqttMessage = MqttMessage(msg.toByteArray())
+            client.publish(topic, mqttMessage.payload, qos, retained)
+            Log.d(this.javaClass.name, "Message published to topic `$topic`: $msg")
+        } catch (e: MqttException) {
+            Log.e(this.javaClass.name, "Error publishing to $topic: " + e.message, e)
+        }
+    }
+
+    fun disconnect() {
+        try {
+            Log.d(this.javaClass.name, "Disconnecting from Broker...")
+            client.disconnect()
+        } catch (e: MqttException) {
+            Log.e(this.javaClass.name, "Error disconnection from Broker: " + e.message, e)
+            e.printStackTrace()
+        }
+    }
+
+    fun isConnected(): Boolean {
+        return client.isConnected
+    }
+}

app/src/main/java/de/chrissthecoder/store/ui/dashboard/DashboardFragment.kt

@@ -0,0 +1,63 @@
+package de.chrissthecoder.store.ui.dashboard
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.ViewModelProvider
+import androidx.viewpager2.widget.ViewPager2
+import androidx.viewpager2.widget.ViewPager2.OnPageChangeCallback
+import com.google.android.material.tabs.TabLayout
+import com.google.android.material.tabs.TabLayout.OnTabSelectedListener
+import de.chrissthecoder.store.adapter.DashboardFragmentPagerAdapter
+import de.chrissthecoder.store.databinding.FragmentDashboardBinding
+
+class DashboardFragment : Fragment() {
+
+    private var _binding: FragmentDashboardBinding? = null
+    private val binding get() = _binding!!
+
+    private lateinit var tabLayout: TabLayout
+    private lateinit var viewPager: ViewPager2
+    private lateinit var adapter: DashboardFragmentPagerAdapter
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?) : View {
+        _binding = FragmentDashboardBinding.inflate(inflater, container, false)
+        val root: View = binding.root
+
+        val dashboardViewModel = ViewModelProvider(this).get(DashboardViewModel::class.java)
+
+        tabLayout = binding.tabLayout
+        viewPager = binding.viewPager
+        adapter = DashboardFragmentPagerAdapter(parentFragmentManager, lifecycle)
+        viewPager.adapter = adapter
+
+        tabLayout.addOnTabSelectedListener(object : OnTabSelectedListener {
+            override fun onTabSelected(tab: TabLayout.Tab?) {
+                if (tab != null) {
+                    viewPager.currentItem = tab.position
+                }
+            }
+
+            override fun onTabUnselected(tab: TabLayout.Tab?) { }
+            override fun onTabReselected(tab: TabLayout.Tab?) { }
+        })
+
+        viewPager.registerOnPageChangeCallback(object : OnPageChangeCallback() {
+            override fun onPageSelected(position: Int) {
+                super.onPageSelected(position)
+                tabLayout.selectTab(tabLayout.getTabAt(position))
+            }
+        })
+
+
+
+        return root
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+}

app/src/main/java/de/chrissthecoder/store/ui/dashboard/DashboardViewModel.kt

@@ -1,10 +1,10 @@
-package de.chrissthecoder.store.ui.home
+package de.chrissthecoder.store.ui.dashboard
 
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 
-class HomeViewModel : ViewModel() {
+class DashboardViewModel : ViewModel() {
 
     private val _text = MutableLiveData<String>().apply {
         value = "This is home Fragment"

app/src/main/java/de/chrissthecoder/store/ui/dashboard/tabfragment/ShoppinglistFragment.kt

@@ -0,0 +1,60 @@
+package de.chrissthecoder.store.ui.dashboard.tabfragment
+
+import android.os.Bundle
+import androidx.fragment.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import de.chrissthecoder.store.R
+
+// TODO: Rename parameter arguments, choose names that match
+// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
+private const val ARG_PARAM1 = "param1"
+private const val ARG_PARAM2 = "param2"
+
+/**
+ * A simple [Fragment] subclass.
+ * Use the [ShoppinglistFragment.newInstance] factory method to
+ * create an instance of this fragment.
+ */
+class ShoppinglistFragment : Fragment() {
+    // TODO: Rename and change types of parameters
+    private var param1: String? = null
+    private var param2: String? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        arguments?.let {
+            param1 = it.getString(ARG_PARAM1)
+            param2 = it.getString(ARG_PARAM2)
+        }
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        // Inflate the layout for this fragment
+        return inflater.inflate(R.layout.fragment_shoppinglist, container, false)
+    }
+
+    companion object {
+        /**
+         * Use this factory method to create a new instance of
+         * this fragment using the provided parameters.
+         *
+         * @param param1 Parameter 1.
+         * @param param2 Parameter 2.
+         * @return A new instance of fragment ShoppinglistFragment.
+         */
+        // TODO: Rename and change types and number of parameters
+        @JvmStatic
+        fun newInstance(param1: String, param2: String) =
+            ShoppinglistFragment().apply {
+                arguments = Bundle().apply {
+                    putString(ARG_PARAM1, param1)
+                    putString(ARG_PARAM2, param2)
+                }
+            }
+    }
+}

app/src/main/java/de/chrissthecoder/store/ui/dashboard/tabfragment/UnderstockFragment.kt

@@ -0,0 +1,60 @@
+package de.chrissthecoder.store.ui.dashboard.tabfragment
+
+import android.os.Bundle
+import androidx.fragment.app.Fragment
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import de.chrissthecoder.store.R
+
+// TODO: Rename parameter arguments, choose names that match
+// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
+private const val ARG_PARAM1 = "param1"
+private const val ARG_PARAM2 = "param2"
+
+/**
+ * A simple [Fragment] subclass.
+ * Use the [UnderstockFragment.newInstance] factory method to
+ * create an instance of this fragment.
+ */
+class UnderstockFragment : Fragment() {
+    // TODO: Rename and change types of parameters
+    private var param1: String? = null
+    private var param2: String? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        arguments?.let {
+            param1 = it.getString(ARG_PARAM1)
+            param2 = it.getString(ARG_PARAM2)
+        }
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        // Inflate the layout for this fragment
+        return inflater.inflate(R.layout.fragment_understock, container, false)
+    }
+
+    companion object {
+        /**
+         * Use this factory method to create a new instance of
+         * this fragment using the provided parameters.
+         *
+         * @param param1 Parameter 1.
+         * @param param2 Parameter 2.
+         * @return A new instance of fragment UnderstockFragment.
+         */
+        // TODO: Rename and change types and number of parameters
+        @JvmStatic
+        fun newInstance(param1: String, param2: String) =
+            UnderstockFragment().apply {
+                arguments = Bundle().apply {
+                    putString(ARG_PARAM1, param1)
+                    putString(ARG_PARAM2, param2)
+                }
+            }
+    }
+}

app/src/main/java/de/chrissthecoder/store/ui/home/HomeFragment.kt

@@ -1,42 +0,0 @@
-package de.chrissthecoder.store.ui.home
-
-import android.os.Bundle
-import android.view.LayoutInflater
-import android.view.View
-import android.view.ViewGroup
-import android.widget.TextView
-import androidx.fragment.app.Fragment
-import androidx.lifecycle.ViewModelProvider
-import de.chrissthecoder.store.databinding.FragmentHomeBinding
-
-class HomeFragment : Fragment() {
-
-    private var _binding: FragmentHomeBinding? = null
-
-    // This property is only valid between onCreateView and
-    // onDestroyView.
-    private val binding get() = _binding!!
-
-    override fun onCreateView(
-        inflater: LayoutInflater,
-        container: ViewGroup?,
-        savedInstanceState: Bundle?
-    ): View {
-        val homeViewModel =
-            ViewModelProvider(this).get(HomeViewModel::class.java)
-
-        _binding = FragmentHomeBinding.inflate(inflater, container, false)
-        val root: View = binding.root
-
-        val textView: TextView = binding.textHome
-        homeViewModel.text.observe(viewLifecycleOwner) {
-            textView.text = it
-        }
-        return root
-    }
-
-    override fun onDestroyView() {
-        super.onDestroyView()
-        _binding = null
-    }
-}

app/src/main/res/layout/fragment_dashboard.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".ui.dashboard.DashboardFragment">
+
+    <com.google.android.material.tabs.TabLayout
+        android:id="@+id/tabLayout"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintVertical_bias="0">
+
+        <com.google.android.material.tabs.TabItem
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/tab_shoppinglist" />
+
+        <com.google.android.material.tabs.TabItem
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/tab_understock" />
+
+    </com.google.android.material.tabs.TabLayout>
+
+    <androidx.viewpager2.widget.ViewPager2
+        android:id="@+id/viewPager"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/tabLayout" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/fragment_shoppinglist.xml

@@ -4,19 +4,16 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context=".ui.home.HomeFragment">
+    tools:context=".ui.dashboard.tabfragment.ShoppinglistFragment">
 
     <TextView
-        android:id="@+id/text_home"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_marginStart="8dp"
+        android:text="Einkaufszettel"
-        android:layout_marginTop="8dp"
-        android:layout_marginEnd="8dp"
         android:textAlignment="center"
-        android:textSize="20sp"
+        android:textSize="32sp"
         app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintVertical_bias="0.5" />
-        app:layout_constraintTop_toTopOf="parent" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/fragment_understock.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".ui.dashboard.tabfragment.UnderstockFragment">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="Minderbestand"
+        android:textAlignment="center"
+        android:textSize="32sp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintVertical_bias="0.5" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/menu/activity_main_drawer.xml

@@ -5,9 +5,9 @@
 
     <group android:checkableBehavior="single">
         <item
-            android:id="@+id/nav_home"
+            android:id="@+id/nav_dashboard"
             android:icon="@drawable/ic_menu_camera"
-            android:title="@string/menu_home" />
+            android:title="@string/menu_dashboard" />
         <item
             android:id="@+id/nav_gallery"
             android:icon="@drawable/ic_menu_gallery"

app/src/main/res/navigation/mobile_navigation.xml

@@ -3,13 +3,13 @@
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/mobile_navigation"
-    app:startDestination="@+id/nav_home">
+    app:startDestination="@+id/nav_dashboard">
 
     <fragment
-        android:id="@+id/nav_home"
+        android:id="@+id/nav_dashboard"
-        android:name="de.chrissthecoder.store.ui.home.HomeFragment"
+        android:name="de.chrissthecoder.store.ui.dashboard.DashboardFragment"
-        android:label="@string/menu_home"
+        android:label="@string/menu_dashboard"
-        tools:layout="@layout/fragment_home" />
+        tools:layout="@layout/fragment_dashboard" />
 
     <fragment
         android:id="@+id/nav_gallery"

app/src/main/res/values/strings.xml

@@ -7,7 +7,10 @@
     <string name="nav_header_desc">Navigation header</string>
     <string name="action_settings">Settings</string>
 
-    <string name="menu_home">Home</string>
+    <string name="menu_dashboard">Dashboard</string>
     <string name="menu_gallery">Gallery</string>
     <string name="menu_slideshow">Slideshow</string>
+
+    <string name="tab_shoppinglist">Einkaufszettel</string>
+    <string name="tab_understock">Minderbestand</string>
 </resources>

build.gradle.kts

@@ -1,5 +1,5 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 plugins {
-    id("com.android.application") version "8.2.2" apply false
+    id("com.android.application") version "8.3.0" apply false
     id("org.jetbrains.kotlin.android") version "1.9.22" apply false
 }

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 #Thu Mar 07 13:51:32 CET 2024
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.2-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists