Use correct async constructor reflection (#512)

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 2.16.4 (Aug 29, 2018)
+- **New** `EpoxyAsyncUtil` and `AsyncEpoxyController` make it easier to use Epoxy's async behavior out of the box
+- **New** Epoxy's background diffing posts messages back to the main thread asynchronously so they are not blocked by waiting for vsync
+
 # 2.16.3 (Aug 24, 2018)
 - **New** Add `AsyncEpoxyController` for easy access to async support. Change background diffing to post asynchronously to the main thread (https://github.com/airbnb/epoxy/pull/509)
 

epoxy-adapter/src/main/java/com/airbnb/epoxy/EpoxyAsyncUtil.java

@@ -2,13 +2,11 @@
 
 import android.os.Build;
 import android.os.Handler;
+import android.os.Handler.Callback;
 import android.os.HandlerThread;
 import android.os.Looper;
 import android.os.Message;
 import android.support.annotation.MainThread;
-import android.support.annotation.Nullable;
-
-import java.lang.reflect.Constructor;
 
 /**
  * Various helpers for running Epoxy operations off the main thread.
@@ -60,18 +58,18 @@ public static Handler createHandler(Looper looper, boolean async) {
       return new Handler(looper);
     }
 
+    // Standard way of exposing async handler on older api's from the support library
+    // https://android.googlesource.com/platform/frameworks/support/+/androidx-master-dev/core
+    // /src/main/java/androidx/core/os/HandlerCompat.java#51
     if (Build.VERSION.SDK_INT >= 28) {
       return Handler.createAsync(looper);
     }
-
-    if (Build.VERSION.SDK_INT >= 17) {
-      Constructor<Handler> handlerConstructor = asyncHandlerConstructor();
-      if (handlerConstructor != null) {
-        try {
-          return handlerConstructor.newInstance(looper, null, true);
-        } catch (Throwable e) {
-          // Fallback
-        }
+    if (Build.VERSION.SDK_INT >= 16) {
+      try {
+        //noinspection JavaReflectionMemberAccess
+        return Handler.class.getDeclaredConstructor(Looper.class, Callback.class, boolean.class)
+            .newInstance(looper, null, true);
+      } catch (Throwable ignored) {
       }
     }
 
@@ -86,18 +84,4 @@ public static Looper buildBackgroundLooper(String threadName) {
     handlerThread.start();
     return handlerThread.getLooper();
   }
-
-  @Nullable
-  private static Constructor<Handler> asyncHandlerConstructor() {
-    try {
-      //noinspection JavaReflectionMemberAccess
-      return Handler.class.getConstructor(
-          Looper.class,
-          Handler.Callback.class,
-          Boolean.class
-      );
-    } catch (Throwable e) {
-      return null;
-    }
-  }
 }

epoxy-adapter/src/main/java/com/airbnb/epoxy/MainThreadExecutor.java

@@ -1,15 +1,14 @@
 package com.airbnb.epoxy;
 
-import android.os.Looper;
-
-import static com.airbnb.epoxy.EpoxyAsyncUtil.createHandler;
+import static com.airbnb.epoxy.EpoxyAsyncUtil.AYSNC_MAIN_THREAD_HANDLER;
+import static com.airbnb.epoxy.EpoxyAsyncUtil.MAIN_THREAD_HANDLER;
 
 class MainThreadExecutor extends HandlerExecutor {
   static final MainThreadExecutor INSTANCE = new MainThreadExecutor(false);
   static final MainThreadExecutor ASYNC_INSTANCE = new MainThreadExecutor(true);
 
   MainThreadExecutor(boolean async) {
-    super(createHandler(Looper.getMainLooper(), async));
+    super(async ? AYSNC_MAIN_THREAD_HANDLER : MAIN_THREAD_HANDLER);
   }
 }
 

gradle.properties

@@ -1,4 +1,4 @@
-VERSION_NAME=2.16.3
+VERSION_NAME=2.16.4
 GROUP=com.airbnb.android
 POM_DESCRIPTION=Epoxy is a system for composing complex screens with a ReyclerView in Android.
 POM_URL=https://github.com/airbnb/epoxy