added first version of paging

build.gradle

@@ -8,8 +8,10 @@ buildscript {
     minVersion = 14
     gradlePluginVersion = '3.5.0'
     kotlinVersion = '1.3.31'
+    coroutine_version = '1.3.0-RC2'
     materialVersion = '1.0.0'
     versionerVersion = '0.4.1'
+    lifecycle_version = '2.2.0-alpha04'
     jUnitVersion = '4.12'
     jUnitTestExtVersion = '1.1.1'
     espressoVersion = '3.2.0'

library/build.gradle

@@ -9,7 +9,7 @@ android {
     minSdkVersion minVersion
     targetSdkVersion targetVersion
     versionCode gitVersioner.versionCode
-    versionName "2.0.1"
+    versionName "2.1.0"
     println('VERSION_CODE: ' + gitVersioner.versionCode)
 
     testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -33,6 +33,13 @@ dependencies {
 
   implementation "androidx.recyclerview:recyclerview:$materialVersion"
 
+  implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutine_version"
+  implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutine_version"
+
+  //lifecycle
+  implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
+  implementation "androidx.lifecycle:lifecycle-runtime-ktx:$lifecycle_version"
+
   testImplementation "junit:junit:$jUnitVersion"
   androidTestImplementation "androidx.test.ext:junit:$jUnitTestExtVersion"
   androidTestImplementation "androidx.test.espresso:espresso-core:$espressoVersion"

library/src/main/java/dev/auxility/baseadapter/EndlessAdapter.java

@@ -0,0 +1,147 @@
+package dev.auxility.baseadapter;
+
+import androidx.annotation.NonNull;
+
+import java.io.Serializable;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+import dev.auxility.baseadapter.item.Item;
+import dev.auxility.baseadapter.misc.function.Predicate;
+
+public class EndlessAdapter<V extends Item> extends AbstractAdapterDecorator<V> {
+
+    private final int threshold;
+    private final OnLoadMoreListener listener;
+    private boolean inProgress = false;
+    private boolean complete = false;
+
+    public EndlessAdapter(
+            @NonNull AbstractAdapter<V> decoratedAdapter,
+            int threshold,
+            OnLoadMoreListener listener
+    ) {
+        super(decoratedAdapter);
+        this.threshold = threshold;
+        this.listener = listener;
+    }
+
+    public EndlessAdapter(int threshold, OnLoadMoreListener listener) {
+        this(new BaseAdapter<V>(), threshold, listener);
+    }
+
+    @Override
+    public int getSize() {
+        int size = getAdapter().getSize();
+        if (size == 0) {
+            checkThreshold(0);
+        }
+        return size;
+    }
+
+    @NonNull
+    @Override
+    public ListIterator<V> listIterator(int index) {
+        return getAdapter().listIterator(index);
+    }
+
+    @NonNull
+    @Override
+    public V get(int index) {
+        checkThreshold(index);
+        return getAdapter().get(index);
+    }
+
+    @NonNull
+    @Override
+    public List<V> items() {
+        return getAdapter().items();
+    }
+
+    @NonNull
+    @Override
+    public V remove(int index) {
+        return getAdapter().remove(index);
+    }
+
+    @Override
+    public boolean removeIf(@NonNull Predicate<V> predicate, boolean withDiffUtil) {
+        return getAdapter().removeIf(predicate, withDiffUtil);
+    }
+
+    @Override
+    public List<V> removeRange(int beginIndex, int endIndex) {
+        return getAdapter().removeRange(beginIndex, endIndex);
+    }
+
+    @Override
+    public void clear(boolean withDiffUtil) {
+        getAdapter().clear();
+    }
+
+    @Override
+    public void add(int index, @NonNull V element) {
+        getAdapter().add(index, element);
+    }
+
+    @Override
+    public boolean addAll(int index, @NonNull Collection<? extends V> c) {
+        return getAdapter().addAll(index, c);
+    }
+
+    @NonNull
+    @Override
+    public V set(int index, @NonNull V element) {
+        return getAdapter().set(index, element);
+    }
+
+    @Override
+    public void set(@NonNull Collection<? extends V> c, boolean withDiffUtil) {
+        getAdapter().set(c, withDiffUtil);
+    }
+
+    @NonNull
+    @Override
+    public Iterator<V> iterator() {
+        return getAdapter().iterator();
+    }
+
+    public int getThreshold() {
+        return threshold;
+    }
+
+    public boolean isInProgress() {
+        return inProgress;
+    }
+
+    public void setInProgress(boolean inProgress) {
+        this.inProgress = inProgress;
+    }
+
+    public boolean isComplete() {
+        return complete;
+    }
+
+    public void setComplete(boolean complete) {
+        this.complete = complete;
+    }
+
+    @Override
+    public void refresh() {
+        getAdapter().refresh();
+    }
+
+    private void checkThreshold(int index) {
+        if (!isComplete() && !isInProgress() && index >= getAdapter().getSize() - threshold) {
+            listener.onLoadMore(getAdapter().getSize());
+        }
+    }
+
+    public interface OnLoadMoreListener extends Serializable {
+
+        void onLoadMore(int currentSize);
+
+    }
+}

sample/src/main/java/dev/auxility/baseadapter/sample/EndlessAdapterSampleFragment.kt

@@ -0,0 +1,13 @@
+package dev.auxility.baseadapter.sample
+
+import androidx.lifecycle.ViewModelProviders
+
+class EndlessAdapterSampleFragment : TabbedFragment() {
+    override val titleRes: Int = R.string.endless_adapter_sample
+
+    override val viewModel: TabbedViewModel by lazy {
+        ViewModelProviders.of(this)
+                .get(EndlessAdapterViewModel::class.java)
+    }
+
+}

sample/src/main/java/dev/auxility/baseadapter/sample/EndlessAdapterViewModel.kt

@@ -0,0 +1,13 @@
+package dev.auxility.baseadapter.sample
+
+import androidx.lifecycle.viewModelScope
+import dev.auxility.baseadapter.Adapter
+import dev.auxility.baseadapter.BaseAdapter
+import dev.auxility.baseadapter.item.TitledItem
+
+class EndlessAdapterViewModel : TabbedViewModel() {
+
+    override val adapter: Adapter<TitledItem> = BaseAdapter(
+            listOf(EndlessRVItem(viewModelScope))
+    )
+}

sample/src/main/java/dev/auxility/baseadapter/sample/EndlessRVItem.kt

@@ -0,0 +1,40 @@
+package dev.auxility.baseadapter.sample
+
+import android.util.Log
+import dev.auxility.baseadapter.EndlessAdapter
+import dev.auxility.baseadapter.item.Item
+import dev.auxility.baseadapter.item.TitledItem
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+
+const val THRESHOLD = 10
+const val PAGE_SIZE = 20
+const val TOTAL_COUNT = 100
+
+class EndlessRVItem(private val scope: CoroutineScope) : TitledItem, EndlessAdapter.OnLoadMoreListener {
+
+    val adapter: EndlessAdapter<Item> = EndlessAdapter(THRESHOLD, this)
+
+    override fun onLoadMore(currentSize: Int) {
+        Log.d("mytag", "loading $PAGE_SIZE items starting at $currentSize from $TOTAL_COUNT")
+        if (currentSize < TOTAL_COUNT) {
+            adapter.isInProgress = true
+            scope.launch {
+                adapter.add(ProgressItem())
+                delay(2000)
+                adapter.remove(adapter.size - 1)
+                adapter.addAll(List(PAGE_SIZE) {
+                    TestItem(currentSize + it)
+                })
+                adapter.isInProgress = false
+            }
+        } else {
+            adapter.isComplete = true
+        }
+    }
+
+    override fun getLayoutId(): Int = R.layout.item_endless_rv
+
+    override fun getTitle(): String = "RecyclerView"
+}

sample/src/main/java/dev/auxility/baseadapter/sample/MainFragment.kt

@@ -11,29 +11,34 @@ import dev.auxility.baseadapter.sample.databinding.FragmentMainBinding
 
 class MainFragment : androidx.fragment.app.Fragment() {
 
-  private lateinit var binding: FragmentMainBinding
+    private lateinit var binding: FragmentMainBinding
 
-  override fun onCreateView(
-    inflater: LayoutInflater,
-    container: ViewGroup?,
-    savedInstanceState: Bundle?
-  ): View? {
-    binding = DataBindingUtil.inflate(
-        inflater,
-        layout.fragment_main, container, false
-    )
-    binding.baseAdapterBtn.setOnClickListener { btn ->
-      btn.findNavController()
-          .navigate(
-              R.id.action_mainFragment_to_baseAdapterSampleFragment
-          )
+    override fun onCreateView(
+            inflater: LayoutInflater,
+            container: ViewGroup?,
+            savedInstanceState: Bundle?
+    ): View? {
+        binding = DataBindingUtil.inflate(
+                inflater,
+                layout.fragment_main, container, false
+        )
+        binding.baseAdapterBtn.setOnClickListener { btn ->
+            btn.findNavController()
+                    .navigate(
+                            R.id.action_mainFragment_to_baseAdapterSampleFragment
+                    )
+        }
+        binding.filterableAdapterBtn.setOnClickListener { btn ->
+            btn.findNavController()
+                    .navigate(
+                            R.id.action_mainFragment_to_filterableAdapterSampleFragment
+                    )
+        }
+        binding.endlessAdapterBtn.setOnClickListener {
+            it.findNavController().navigate(
+                    R.id.action_mainFragment_to_endlessAdapterSampleFragment
+            )
+        }
+        return binding.root
     }
-    binding.filterableAdapterBtn.setOnClickListener { btn ->
-      btn.findNavController()
-          .navigate(
-              R.id.action_mainFragment_to_filterableAdapterSampleFragment
-          )
-    }
-    return binding.root
-  }
 }

sample/src/main/java/dev/auxility/baseadapter/sample/ProgressItem.kt

@@ -0,0 +1,7 @@
+package dev.auxility.baseadapter.sample
+
+import dev.auxility.baseadapter.item.Item
+
+class ProgressItem : Item {
+    override fun getLayoutId(): Int = R.layout.item_progress
+}

sample/src/main/res/layout/fragment_main.xml

@@ -47,13 +47,25 @@
         android:layout_height="wrap_content"
         android:layout_marginTop="24dp"
         android:text="@string/filterableadapter_sample"
-        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/endlessAdapterBtn"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintHorizontal_bias="0.5"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/baseAdapterBtn"
-        app:layout_constraintWidth_percent="0.7"
-        />
+        app:layout_constraintWidth_percent="0.7" />
+
+    <Button
+        android:id="@+id/endlessAdapterBtn"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="24dp"
+        android:text="@string/endless_adapter_sample"
+        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/filterableAdapterBtn"
+        app:layout_constraintWidth_percent="0.7" />
 
   </androidx.constraintlayout.widget.ConstraintLayout>
 </layout>

sample/src/main/res/layout/item_endless_rv.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout 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">
+
+    <data>
+
+        <variable
+            name="item"
+            type="dev.auxility.baseadapter.sample.EndlessRVItem" />
+    </data>
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/recyclerView"
+        adapter="@{item.adapter}"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
+        tools:listitem="@layout/item_rv_sample" />
+
+</layout>