diff --git a/android/src/main/java/com/befovy/fijkplayer/FijkEngine.java b/android/src/main/java/com/befovy/fijkplayer/FijkEngine.java
index 6ac4e9d8..99c8bf59 100644
--- a/android/src/main/java/com/befovy/fijkplayer/FijkEngine.java
+++ b/android/src/main/java/com/befovy/fijkplayer/FijkEngine.java
@@ -33,15 +33,18 @@
 
 interface FijkEngine {
 
+    @Nullable
     TextureRegistry.SurfaceTextureEntry createSurfaceEntry();
 
+    @Nullable
     BinaryMessenger messenger();
 
+    @Nullable
     Context context();
 
+    @Nullable
     String lookupKeyForAsset(@NonNull String asset, @Nullable String packageName);
 
-
     void onPlayingChange(int delta);
 
     void onPlayableChange(int delta);
diff --git a/android/src/main/java/com/befovy/fijkplayer/FijkPlayer.java b/android/src/main/java/com/befovy/fijkplayer/FijkPlayer.java
index 9c1877a7..2e8e9531 100644
--- a/android/src/main/java/com/befovy/fijkplayer/FijkPlayer.java
+++ b/android/src/main/java/com/befovy/fijkplayer/FijkPlayer.java
@@ -22,6 +22,7 @@
 
 package com.befovy.fijkplayer;
 
+import android.content.Context;
 import android.content.res.AssetManager;
 import android.graphics.Bitmap;
 import android.graphics.SurfaceTexture;
@@ -131,7 +132,7 @@ int getPlayerId() {
     void setup() {
         if (mJustSurface)
             return;
-        if (mHostOptions.getIntOption(HostOption.ENABLE_SNAPSHOT,0) > 0) {
+        if (mHostOptions.getIntOption(HostOption.ENABLE_SNAPSHOT, 0) > 0) {
             mIjkMediaPlayer.setAmcGlesRender();
             mIjkMediaPlayer.setOption(IjkMediaPlayer.OPT_CATEGORY_PLAYER, "overlay-format", "fcc-_es2");
         }
@@ -142,13 +143,20 @@ long setupSurface() {
         if (mSurfaceTextureEntry == null) {
             TextureRegistry.SurfaceTextureEntry surfaceTextureEntry = mEngine.createSurfaceEntry();
             mSurfaceTextureEntry = surfaceTextureEntry;
-            mSurfaceTexture = surfaceTextureEntry.surfaceTexture();
-            mSurface = new Surface(mSurfaceTexture);
+            if (surfaceTextureEntry != null) {
+                mSurfaceTexture = surfaceTextureEntry.surfaceTexture();
+                mSurface = new Surface(mSurfaceTexture);
+            }
             if (!mJustSurface) {
                 mIjkMediaPlayer.setSurface(mSurface);
             }
         }
-        return mSurfaceTextureEntry.id();
+        if (mSurfaceTextureEntry != null)
+            return mSurfaceTextureEntry.id();
+        else {
+            Log.e("FIJKPLAYER", "setup surface, null SurfaceTextureEntry");
+            return 0;
+        }
     }
 
     void release() {
@@ -332,7 +340,7 @@ private void applyOptions(Object options) {
             for (Object o : optionsMap.keySet()) {
                 Object option = optionsMap.get(o);
                 if (o instanceof Integer && option instanceof Map) {
-                    Integer cat = (Integer) o;
+                    int cat = (Integer) o;
                     Map optionMap = (Map) option;
                     for (Object key : optionMap.keySet()) {
                         Object value = optionMap.get(key);
@@ -404,11 +412,12 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result
                 }
             }
             try {
-                if (openAsset) {
-                    AssetManager assetManager = mEngine.context().getAssets();
+                Context context = mEngine.context();
+                if (openAsset && context != null) {
+                    AssetManager assetManager = context.getAssets();
                     InputStream is = assetManager.open(uri.getPath() != null ? uri.getPath() : "", AssetManager.ACCESS_RANDOM);
                     mIjkMediaPlayer.setDataSource(new RawMediaDataSource(is));
-                } else {
+                } else if (context != null){
                     if (TextUtils.isEmpty(uri.getScheme()) || "file".equals(uri.getScheme())) {
                         String path = uri.getPath() != null ? uri.getPath() : "";
                         IMediaDataSource dataSource = new FileMediaDataSource(new File(path));
@@ -416,8 +425,13 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result
                     } else {
                         mIjkMediaPlayer.setDataSource(mEngine.context(), uri);
                     }
+                } else {
+                    Log.e("FIJKPLAYER", "context null, can't setDataSource");
                 }
                 handleEvent(PLAYBACK_STATE_CHANGED, initialized, -1, null);
+                if (context == null) {
+                    handleEvent(PLAYBACK_STATE_CHANGED, error, -1, null);
+                }
                 result.success(null);
             } catch (FileNotFoundException e) {
                 result.error("-875574348", "Local File not found:" + e.getMessage(), null);
@@ -468,7 +482,7 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result
         } else if (call.method.equals("snapshot")) {
             if (mHostOptions.getIntOption(HostOption.ENABLE_SNAPSHOT, 0) > 0) {
                 mIjkMediaPlayer.snapShot();
-            } else  {
+            } else {
                 mMethodChannel.invokeMethod("_onSnapshot", "not support");
             }
             result.success(null);
diff --git a/android/src/main/java/com/befovy/fijkplayer/FijkPlugin.java b/android/src/main/java/com/befovy/fijkplayer/FijkPlugin.java
index b6f91c0c..78f60c89 100644
--- a/android/src/main/java/com/befovy/fijkplayer/FijkPlugin.java
+++ b/android/src/main/java/com/befovy/fijkplayer/FijkPlugin.java
@@ -151,7 +151,6 @@ public void onDetachedFromActivityForConfigChanges() {
     @Override
     public void onReattachedToActivityForConfigChanges(ActivityPluginBinding binding) {
         mActivity = new WeakReference<>(binding.getActivity());
-
         if (mActivity.get() instanceof FijkVolume.CanListenVolumeKey) {
             FijkVolume.CanListenVolumeKey canListenVolumeKey = (FijkVolume.CanListenVolumeKey) mActivity.get();
             canListenVolumeKey.setVolumeKeyListener(this);
@@ -164,6 +163,7 @@ public void onDetachedFromActivity() {
     }
 
     @Override
+    @Nullable
     public TextureRegistry.SurfaceTextureEntry createSurfaceEntry() {
         if (mBinding != null) {
             return mBinding.getTextureRegistry().createSurfaceTexture();
@@ -174,6 +174,7 @@ public TextureRegistry.SurfaceTextureEntry createSurfaceEntry() {
     }
 
     @Override
+    @Nullable
     public BinaryMessenger messenger() {
         if (mBinding != null) {
             return mBinding.getBinaryMessenger();
@@ -184,19 +185,27 @@ public BinaryMessenger messenger() {
     }
 
     @Override
+    @Nullable
     public Context context() {
-        return mContext.get();
+        if (mContext != null)
+            return mContext.get();
+        else
+            return null;
     }
 
+    @Nullable
     private Activity activity() {
         if (mRegistrar != null) {
             return mRegistrar.activity();
-        } else {
+        } else if (mActivity != null) {
             return mActivity.get();
+        } else {
+            return null;
         }
     }
 
     @Override
+    @Nullable
     public String lookupKeyForAsset(@NonNull String asset, @Nullable String packageName) {
         String path = null;
         if (mBinding != null) {
@@ -262,6 +271,7 @@ public void onCancel(Object o) {
 
     @Override
     public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
+        Activity activity;
         switch (call.method) {
             case "getPlatformVersion":
                 result.success("Android " + android.os.Build.VERSION.RELEASE);
@@ -305,8 +315,8 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
             }
             case "setOrientationPortrait":
                 boolean changedPort = false;
-                if (activity() != null) {
-                    final Activity activity = activity();
+                activity = activity();
+                if (activity != null) {
                     int current_orientation = activity.getResources().getConfiguration().orientation;
                     if (current_orientation == Configuration.ORIENTATION_LANDSCAPE) {
                         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
@@ -321,8 +331,8 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
                 break;
             case "setOrientationLandscape":
                 boolean changedLand = false;
-                if (activity() != null) {
-                    final Activity activity = activity();
+                activity = activity();
+                if (activity != null) {
                     int current_orientation = activity.getResources().getConfiguration().orientation;
                     if (current_orientation == Configuration.ORIENTATION_PORTRAIT) {
                         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
@@ -336,8 +346,8 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
                 result.success(changedLand);
                 break;
             case "setOrientationAuto":
-                if (activity() != null) {
-                    final Activity activity = activity();
+                activity = activity();
+                if (activity != null) {
                     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
                         activity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_FULL_USER);
                     } else {
@@ -481,7 +491,6 @@ public void setScreenOn(boolean on) {
      */
     private boolean isScreenKeptOn() {
         Activity activity = activity();
-
         if (activity == null || activity.getWindow() == null)
             return false;
         int flag = activity.getWindow().getAttributes().flags;
@@ -491,12 +500,11 @@ private boolean isScreenKeptOn() {
 
     private float getScreenBrightness() {
         Activity activity = activity();
-
         if (activity == null || activity.getWindow() == null)
             return 0;
         float brightness = activity.getWindow().getAttributes().screenBrightness;
         if (brightness < 0) {
-            Context context = mContext.get();
+            Context context = context();
             Log.w("FIJKPLAYER", "window attribute brightness less than 0");
             try {
                 if (context != null) {
@@ -512,7 +520,6 @@ private float getScreenBrightness() {
 
     private void setScreenBrightness(float brightness) {
         Activity activity = activity();
-
         if (activity == null || activity.getWindow() == null)
             return;
         WindowManager.LayoutParams layoutParams = activity.getWindow().getAttributes();
@@ -549,7 +556,7 @@ private void requestAudioFocus() {
     }
 
     @TargetApi(26)
-    @SuppressWarnings("deprecation")
+    // @SuppressWarnings("deprecation")
     private void abandonAudioFocus() {
         AudioManager audioManager = audioManager();
         if (audioManager == null)
@@ -581,7 +588,7 @@ public void audioFocus(boolean request) {
 
     @Nullable
     private AudioManager audioManager() {
-        Context context = mContext.get();
+        Context context = context();
         if (context != null) {
             return (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
         } else {