Added reusable loading, empty and error UI components with testing

app/src/main/java/deakin/gopher/guardian/WelcomeActivity.kt

@@ -1,11 +1,67 @@
 package deakin.gopher.guardian
 
 import android.os.Bundle
+import android.os.Handler
+import android.os.Looper
+import android.view.View
+import android.widget.Button
+import deakin.gopher.guardian.components.EmptyView
+import deakin.gopher.guardian.components.ErrorView
+import deakin.gopher.guardian.components.LoadingView
 import androidx.appcompat.app.AppCompatActivity
 
 class WelcomeActivity : AppCompatActivity() {
+
+    private lateinit var loadingView: LoadingView
+    private lateinit var emptyView: EmptyView
+    private lateinit var errorView: ErrorView
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_welcome) // This links to your activity_welcome.xml
+
+        loadingView = findViewById(R.id.loadingView)
+        emptyView = findViewById(R.id.emptyView)
+        errorView = findViewById(R.id.errorView)
+
+        val btnShowLoading = findViewById<Button>(R.id.btnShowLoading)
+        val btnShowEmpty = findViewById<Button>(R.id.btnShowEmpty)
+        val btnShowError = findViewById<Button>(R.id.btnShowError)
+        val btnHideAll = findViewById<Button>(R.id.btnHideAll)
+
+        btnShowLoading.setOnClickListener {
+            hideAllStateViews()
+            loadingView.show()
+        }
+
+        btnShowEmpty.setOnClickListener {
+            hideAllStateViews()
+            emptyView.show("No records found")
+        }
+
+        btnShowError.setOnClickListener {
+            hideAllStateViews()
+            errorView.show("Failed to load data")
+        }
+
+        btnHideAll.setOnClickListener {
+            hideAllStateViews()
+        }
+
+        errorView.setOnRetryClick {
+            hideAllStateViews()
+            loadingView.show()
+
+            loadingView.postDelayed({
+                loadingView.hide()
+                emptyView.show("Retry completed, but no data available")
+            }, 2000)
+        }
+    }
+
+    private fun hideAllStateViews() {
+        loadingView.hide()
+        emptyView.hide()
+        errorView.hide()
     }
-}
+}

app/src/main/java/deakin/gopher/guardian/components/EmptyView.kt

@@ -0,0 +1,36 @@
+package deakin.gopher.guardian.components
+import android.content.Context
+import android.util.AttributeSet
+import android.view.LayoutInflater
+import android.widget.FrameLayout
+import android.widget.TextView
+import deakin.gopher.guardian.R
+
+class EmptyView @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null
+) : FrameLayout(context, attrs) {
+
+    private val message: TextView
+
+    init {
+        LayoutInflater.from(context).inflate(R.layout.view_empty, this, true)
+        visibility = GONE
+        message = findViewById(R.id.emptyMessage)
+    }
+
+    fun setMessage(text: String) {
+        message.text = text
+    }
+
+    fun show(messageText: String? = null) {
+        if (messageText != null) {
+            message.text = messageText
+        }
+        visibility = VISIBLE
+    }
+
+    fun hide() {
+        visibility = GONE
+    }
+}

app/src/main/java/deakin/gopher/guardian/components/ErrorView.kt

@@ -0,0 +1,44 @@
+package deakin.gopher.guardian.components
+import android.content.Context
+import android.util.AttributeSet
+import android.view.LayoutInflater
+import android.widget.Button
+import android.widget.FrameLayout
+import android.widget.TextView
+import deakin.gopher.guardian.R
+
+class ErrorView @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null
+) : FrameLayout(context, attrs) {
+
+    private val message: TextView
+    private val retryButton: Button
+
+    init {
+        LayoutInflater.from(context).inflate(R.layout.view_error, this, true)
+        visibility = GONE
+
+        message = findViewById(R.id.errorMessage)
+        retryButton = findViewById(R.id.retryButton)
+    }
+
+    fun setMessage(text: String) {
+        message.text = text
+    }
+
+    fun setOnRetryClick(listener: () -> Unit) {
+        retryButton.setOnClickListener { listener() }
+    }
+
+    fun show(messageText: String? = null) {
+        if (messageText != null) {
+            message.text = messageText
+        }
+        visibility = VISIBLE
+    }
+
+    fun hide() {
+        visibility = GONE
+    }
+}

app/src/main/java/deakin/gopher/guardian/components/LoadingView.kt

@@ -0,0 +1,25 @@
+package deakin.gopher.guardian.components
+import android.content.Context
+import android.util.AttributeSet
+import android.view.LayoutInflater
+import android.widget.FrameLayout
+import deakin.gopher.guardian.R
+
+class LoadingView @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null
+) : FrameLayout(context, attrs) {
+
+    init {
+        LayoutInflater.from(context).inflate(R.layout.view_loading, this, true)
+        visibility = GONE
+    }
+
+    fun show() {
+        visibility = VISIBLE
+    }
+
+    fun hide() {
+        visibility = GONE
+    }
+}

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

@@ -1,38 +1,98 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
+<FrameLayout 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=".WelcomeActivity"
-    android:padding="16dp">
-
-    <!-- Welcome Message -->
-    <TextView
-        android:id="@+id/welcomeMessage"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="@string/welcome_message"
-        android:textSize="22sp"
-        android:textStyle="bold"
-        app:layout_constraintTop_toTopOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        android:layout_marginTop="50dp" />
-
-    <!-- Detailed Description -->
-    <TextView
-        android:id="@+id/welcomeDescription"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="@string/welcome_description"
-        android:textSize="16sp"
-        app:layout_constraintTop_toBottomOf="@id/welcomeMessage"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        android:layout_marginTop="20dp"
-        android:padding="16dp" />
-
-</androidx.constraintlayout.widget.ConstraintLayout>
+    tools:context=".WelcomeActivity">
 
+    <!-- YOUR ORIGINAL CONTENT -->
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:id="@+id/contentLayout"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:padding="16dp">
+
+        <!-- Welcome Message -->
+        <TextView
+            android:id="@+id/welcomeMessage"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/welcome_message"
+            android:textSize="22sp"
+            android:textStyle="bold"
+            android:layout_marginTop="50dp"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintEnd_toEndOf="parent" />
+
+        <!-- Description -->
+        <TextView
+            android:id="@+id/welcomeDescription"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/welcome_description"
+            android:textSize="16sp"
+            android:layout_marginTop="20dp"
+            android:padding="16dp"
+            app:layout_constraintTop_toBottomOf="@id/welcomeMessage"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintEnd_toEndOf="parent" />
+
+        <!-- TEST BUTTONS -->
+        <Button
+            android:id="@+id/btnShowLoading"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Show Loading"
+            app:layout_constraintTop_toBottomOf="@id/welcomeDescription"
+            app:layout_constraintStart_toStartOf="parent"
+            android:layout_marginTop="20dp" />
+
+        <Button
+            android:id="@+id/btnShowEmpty"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Show Empty"
+            app:layout_constraintTop_toBottomOf="@id/btnShowLoading"
+            app:layout_constraintStart_toStartOf="parent"
+            android:layout_marginTop="12dp" />
+
+        <Button
+            android:id="@+id/btnShowError"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Show Error"
+            app:layout_constraintTop_toBottomOf="@id/btnShowEmpty"
+            app:layout_constraintStart_toStartOf="parent"
+            android:layout_marginTop="12dp" />
+
+        <Button
+            android:id="@+id/btnHideAll"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Hide All"
+            app:layout_constraintTop_toBottomOf="@id/btnShowError"
+            app:layout_constraintStart_toStartOf="parent"
+            android:layout_marginTop="12dp" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+
+    <!-- OVERLAY VIEWS (VERY IMPORTANT: OUTSIDE ConstraintLayout) -->
+
+    <deakin.gopher.guardian.components.LoadingView
+        android:id="@+id/loadingView"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+    <deakin.gopher.guardian.components.EmptyView
+        android:id="@+id/emptyView"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+    <deakin.gopher.guardian.components.ErrorView
+        android:id="@+id/errorView"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+</FrameLayout>

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

@@ -0,0 +1,16 @@
+<?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:gravity="center"
+    android:orientation="vertical"
+    android:padding="24dp">
+
+    <TextView
+        android:id="@+id/emptyMessage"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="No data available"
+        android:textSize="16sp" />
+
+</LinearLayout>

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

@@ -0,0 +1,23 @@
+<?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:gravity="center"
+    android:orientation="vertical"
+    android:padding="24dp">
+
+    <TextView
+        android:id="@+id/errorMessage"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginBottom="12dp"
+        android:text="Something went wrong"
+        android:textSize="16sp" />
+
+    <Button
+        android:id="@+id/retryButton"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Retry" />
+
+</LinearLayout>

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

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:foregroundGravity="center"
+    android:clickable="true"
+    android:focusable="true">
+
+    <ProgressBar
+        android:id="@+id/progressBar"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center" />
+
+</FrameLayout>