Sample app : Simplify Room + LiveData

app/src/main/java/com/mikepenz/fastadapter/app/PagedActivity.kt

@@ -1,7 +1,11 @@
 package com.mikepenz.fastadapter.app
 
+import android.graphics.Color
 import android.os.Bundle
 import android.os.Handler
+import android.view.Menu
+import android.view.MenuItem
+import android.widget.Toast
 import androidx.appcompat.app.AppCompatActivity
 import androidx.lifecycle.ViewModelProvider
 import androidx.recyclerview.widget.AsyncDifferConfig
@@ -14,6 +18,10 @@ import com.mikepenz.fastadapter.app.paged.DemoEntity
 import com.mikepenz.fastadapter.app.paged.DemoEntityViewModel
 import com.mikepenz.fastadapter.paged.PagedModelAdapter
 import com.mikepenz.fastadapter.select.getSelectExtension
+import com.mikepenz.iconics.IconicsDrawable
+import com.mikepenz.iconics.typeface.library.materialdesigniconic.MaterialDesignIconic
+import com.mikepenz.iconics.utils.actionBar
+import com.mikepenz.iconics.utils.colorInt
 
 
 class PagedActivity : AppCompatActivity() {
@@ -25,6 +33,8 @@ class PagedActivity : AppCompatActivity() {
     //save our FastAdapter
     private lateinit var mItemAdapter: PagedModelAdapter<DemoEntity, SimpleImageItem>
 
+    private lateinit var viewModel: DemoEntityViewModel
+
     override fun onCreate(savedInstanceState: Bundle?) {
         //create the activity
         super.onCreate(savedInstanceState)
@@ -36,22 +46,27 @@ class PagedActivity : AppCompatActivity() {
         setSupportActionBar(binding.toolbar)
         supportActionBar?.setTitle(R.string.sample_paged_list)
 
-        val asyncDifferConfig = AsyncDifferConfig.Builder<DemoEntity>(object : DiffUtil.ItemCallback<DemoEntity>() {
-            override fun areItemsTheSame(oldItem: DemoEntity, newItem: DemoEntity): Boolean {
-                return oldItem.identifier == newItem.identifier
-            }
+        val asyncDifferConfig =
+            AsyncDifferConfig.Builder(object : DiffUtil.ItemCallback<DemoEntity>() {
+                override fun areItemsTheSame(oldItem: DemoEntity, newItem: DemoEntity): Boolean {
+                    return oldItem.identifier == newItem.identifier
+                }
 
-            override fun areContentsTheSame(oldItem: DemoEntity, newItem: DemoEntity): Boolean {
-                return oldItem == newItem
-            }
-        }).build()
+                override fun areContentsTheSame(oldItem: DemoEntity, newItem: DemoEntity): Boolean {
+                    return oldItem.data1 == newItem.data1
+                }
+            }).build()
 
         //create our ItemAdapter which will host our items
-        mItemAdapter = PagedModelAdapter<DemoEntity, SimpleImageItem>(asyncDifferConfig, { arg: Int -> SimpleImageItem().setPlaceholder() }) {
-            SimpleImageItem().withName(it.data1 ?: "").withDescription(it.data2 ?: "").apply {
+        mItemAdapter = PagedModelAdapter<DemoEntity, SimpleImageItem>(
+            asyncDifferConfig,
+            { SimpleImageItem().setPlaceholder() }) {
+            SimpleImageItem().apply {
                 identifier = it.identifier.toLong()
                 isSelectable = true
                 withImage("https://raw.githubusercontent.com/mikepenz/earthview-wallpapers/develop/thumb/yang_zhuo_yong_cuo,_tibet-china-63.jpg")
+                withName(it.data1 ?: "")
+                withDescription(it.data2 ?: "")
             }
         }
 
@@ -67,14 +82,17 @@ class PagedActivity : AppCompatActivity() {
         binding.rv.layoutManager = LinearLayoutManager(this)
         binding.rv.adapter = mFastAdapter
 
-        val viewModel = ViewModelProvider(this, DemoEntityViewModel.DemoEntityViewModelFactory(this.application))
+        viewModel = ViewModelProvider(
+            this,
+            DemoEntityViewModel.DemoEntityViewModelFactory(this.application)
+        )
             .get(DemoEntityViewModel::class.java)
 
         //listen to data changes and pass it to adapter for displaying in recycler view
         viewModel.demoEntitiesList.observe(this, { t -> mItemAdapter.submitList(t!!) })
 
         //if we do this. the first added items will be animated :D
-        Handler().postDelayed({
+        Handler(mainLooper).postDelayed({
             //restore selections (this has to be done after the items were added
             mFastAdapter.withSavedInstanceState(savedInstanceState)
         }, 50)
@@ -92,6 +110,32 @@ class PagedActivity : AppCompatActivity() {
         super.onSaveInstanceState(outState)
     }
 
+    override fun onCreateOptionsMenu(menu: Menu): Boolean {
+        val inflater = menuInflater
+        inflater.inflate(R.menu.refresh, menu)
+        menu.findItem(R.id.item_refresh).icon =
+            IconicsDrawable(this, MaterialDesignIconic.Icon.gmi_refresh).apply {
+                colorInt = Color.BLACK; actionBar()
+            }
+        return true
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        //handle the click on the back arrow click
+        return when (item.itemId) {
+            android.R.id.home -> {
+                onBackPressed()
+                true
+            }
+            R.id.item_refresh -> {
+                viewModel.updateEntities()
+                Toast.makeText(this, "Refresh DB", Toast.LENGTH_SHORT).show()
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
     override fun onSupportNavigateUp(): Boolean {
         onBackPressed()
         return true

app/src/main/java/com/mikepenz/fastadapter/app/items/SimpleImageItem.kt

@@ -23,7 +23,8 @@ class SimpleImageItem : BaseItem<SimpleImageItem.ViewHolder>() {
     private var mImageUrl: String? = null
     private var mName: String? = null
     private var mDescription: String? = null
-    private var isPlaceholder: Boolean = false // True when used as placeholderInterceptor by PagedModelAdapter
+    private var isPlaceholder: Boolean =
+        false // True when used as placeholderInterceptor by PagedModelAdapter
 
     /**
      * defines the type defining this item. must be unique. preferably an id
@@ -85,10 +86,18 @@ class SimpleImageItem : BaseItem<SimpleImageItem.ViewHolder>() {
         holder.imageView.setImageBitmap(null)
 
         //set the background for the item
-        val color = ctx.getThemeColor(R.attr.colorPrimary, ContextCompat.getColor(ctx, R.color.colorPrimary))
+        val color = ctx.getThemeColor(
+            R.attr.colorPrimary,
+            ContextCompat.getColor(ctx, R.color.colorPrimary)
+        )
 
         holder.view.clearAnimation()
-        holder.view.foreground = FastAdapterUIUtils.getSelectablePressedBackground(ctx, FastAdapterUIUtils.adjustAlpha(color, 100), 50, true)
+        holder.view.foreground = FastAdapterUIUtils.getSelectablePressedBackground(
+            ctx,
+            FastAdapterUIUtils.adjustAlpha(color, 100),
+            50,
+            true
+        )
 
         //load glide
         holder.imageView.load(mImageUrl) {

app/src/main/java/com/mikepenz/fastadapter/app/paged/DemoEntityLocalDAO.kt

@@ -1,19 +1,24 @@
 package com.mikepenz.fastadapter.app.paged
 
+import androidx.paging.DataSource
 import androidx.room.Dao
 import androidx.room.Insert
 import androidx.room.Query
 
+
 /**
  * https://www.zoftino.com/pagination-in-android-using-paging-library
  */
 @Dao
 interface DemoEntityLocalDAO {
     //to fetch data required to display in each page
-    @Query("SELECT * FROM DemoEntity WHERE  identifier >= :id ORDER BY identifier LIMIT :size")
-    fun getDemoEntitiesBySize(id: Int, size: Int): List<DemoEntity>
+    @Query("SELECT * FROM DemoEntity")
+    fun getAll(): DataSource.Factory<Int, DemoEntity>
 
     //this is used to populate db
     @Insert
     fun insertDemoEntities(demoEntities: List<DemoEntity>)
+
+    @Query("UPDATE DemoEntity SET data1 = -data1")
+    fun updateDemoEntities()
 }

app/src/main/java/com/mikepenz/fastadapter/app/paged/DemoEntityViewModel.kt

@@ -1,39 +1,46 @@
 package com.mikepenz.fastadapter.app.paged
 
 import android.app.Application
-
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
 import androidx.paging.LivePagedListBuilder
 import androidx.paging.PagedList
+import io.reactivex.Completable
+import io.reactivex.android.schedulers.AndroidSchedulers
+import io.reactivex.schedulers.Schedulers
+
 
 /**
  * https://www.zoftino.com/pagination-in-android-using-paging-library
  */
-class DemoEntityViewModel(application: Application) : ViewModel() {
+class DemoEntityViewModel(val application: Application) : ViewModel() {
     //PagedList controls data loading using data source
+    private val dao: DemoEntityLocalDAO =
+        LocalRepository.getDemoEntityDB(application).demoEntityDAO()
     var demoEntitiesList: LiveData<PagedList<DemoEntity>>
 
     init {
-        //instantiate DemoEntitiesDataSourceFactory
-        val factory = DemoEntitiesDataSourceFactory(application)
+        val pagedListConfig = PagedList.Config.Builder()
+            .setPageSize(20)
+            .setPrefetchDistance(20)
+            .setEnablePlaceholders(true)
+            .build()
 
-        //create PagedList Config
-        val config = PagedList.Config.Builder()
-                .setEnablePlaceholders(true)
-                .setInitialLoadSizeHint(10)
-                .setPageSize(5)
-                .build()
+        demoEntitiesList = LivePagedListBuilder(dao.getAll(), pagedListConfig).build()
+    }
 
-        //create LiveData object using LivePagedListBuilder which takes
-        //data source factory and page config as params
-        demoEntitiesList = LivePagedListBuilder(factory, config).build()
+    fun updateEntities() {
+        Completable.fromRunnable { dao.updateDemoEntities() }
+            .subscribeOn(Schedulers.io())
+            .observeOn(AndroidSchedulers.mainThread())
+            .subscribe()
     }
 
     //factory for creating view model,
     // required because we need to pass Application to view model object
-    class DemoEntityViewModelFactory(private val mApplication: Application) : ViewModelProvider.NewInstanceFactory() {
+    class DemoEntityViewModelFactory(private val mApplication: Application) :
+        ViewModelProvider.NewInstanceFactory() {
         override fun <T : ViewModel> create(viewModel: Class<T>): T {
             return DemoEntityViewModel(mApplication) as T
         }