add favorite list to home screen

app/src/main/java/org/mosad/teapod/util/CacheHelper.kt

@@ -0,0 +1,47 @@
+package org.mosad.teapod.util
+
+import android.content.Context
+import android.util.Log
+import com.google.gson.Gson
+import com.google.gson.GsonBuilder
+import kotlinx.coroutines.*
+import java.io.File
+
+/**
+ * myList should be saved in a db
+ */
+object CacheHelper {
+
+    private const val fileNameMyList = "my_list.json"
+
+    val myList = ArrayList<String>() // a list of saved links
+
+    fun load(context: Context) {
+        val file = File(context.filesDir, fileNameMyList)
+
+        if (!file.exists()) runBlocking { saveMyList(context).join() }
+
+        myList.clear()
+        myList.addAll(
+            GsonBuilder().create().fromJson(file.readText(), ArrayList<String>().javaClass)
+        )
+    }
+
+
+    fun saveMyList(context: Context): Job {
+        val file = File(context.filesDir, fileNameMyList)
+
+        return GlobalScope.launch(Dispatchers.IO) {
+            file.writeText(Gson().toJson(myList))
+        }
+    }
+
+    private fun save(file: File, text: String) {
+        try {
+            file.writeText(text)
+        } catch (ex: Exception) {
+            Log.e(javaClass.name, "failed to write file \"${file.absoluteFile}\"", ex)
+        }
+    }
+
+}

app/src/main/java/org/mosad/teapod/util/adapter/MediaItemAdapter.kt

@@ -11,9 +11,8 @@ import kotlinx.android.synthetic.main.item_media.view.*
 import org.mosad.teapod.R
 import org.mosad.teapod.util.Media
 import java.util.*
-import kotlin.collections.ArrayList
 
-class MediaItemAdapter(private val media: ArrayList<Media>) : RecyclerView.Adapter<MediaItemAdapter.ViewHolder>(), Filterable {
+class MediaItemAdapter(private val media: List<Media>) : RecyclerView.Adapter<MediaItemAdapter.ViewHolder>(), Filterable {
 
     var onItemClick: ((Media, Int) -> Unit)? = null
     private val filter = MediaFilter()
@@ -72,7 +71,7 @@ class MediaItemAdapter(private val media: ArrayList<Media>) : RecyclerView.Adapt
          * suppressing unchecked cast is safe, since we only use Media
          */
         override fun publishResults(constraint: CharSequence?, results: FilterResults?) {
-            filteredMedia = results?.values as java.util.ArrayList<Media>
+            filteredMedia = results?.values as List<Media>
             notifyDataSetChanged()
         }
     }