diff --git a/.idea/dictionaries/Jacksgong.xml b/.idea/dictionaries/Jacksgong.xml
index 0c7ccdd2..69d88038 100644
--- a/.idea/dictionaries/Jacksgong.xml
+++ b/.idea/dictionaries/Jacksgong.xml
@@ -1,11 +1,18 @@
 <component name="ProjectDictionaryState">
   <dictionary name="Jacksgong">
     <words>
+      <w>buildship</w>
       <w>chunked</w>
+      <w>classpathentry</w>
       <w>dreamtobe</w>
       <w>etag</w>
       <w>filedownloader</w>
+      <w>gradleclasspathcontainer</w>
+      <w>gradleprojectbuilder</w>
+      <w>gradleprojectnature</w>
       <w>jacksgong</w>
+      <w>javabuilder</w>
+      <w>javanature</w>
       <w>liulishuo</w>
       <w>okhttp</w>
       <w>robolectric</w>
diff --git a/.idea/inspectionProfiles/Project_Default.xml b/.idea/inspectionProfiles/Project_Default.xml
index 95cbb5f6..b5e78d48 100644
--- a/.idea/inspectionProfiles/Project_Default.xml
+++ b/.idea/inspectionProfiles/Project_Default.xml
@@ -1,11 +1,9 @@
 <component name="InspectionProjectProfileManager">
   <profile version="1.0">
     <option name="myName" value="Project Default" />
+    <inspection_tool class="AndroidLintMinSdkTooLow" enabled="false" level="WARNING" enabled_by_default="false" />
+    <inspection_tool class="AndroidLintMissingPermission" enabled="false" level="ERROR" enabled_by_default="false" />
     <inspection_tool class="DanglingJavadoc" enabled="false" level="WARNING" enabled_by_default="false" />
-    <inspection_tool class="LoggerInitializedWithForeignClass" enabled="false" level="WARNING" enabled_by_default="false">
-      <option name="loggerClassName" value="org.apache.log4j.Logger,org.slf4j.LoggerFactory,org.apache.commons.logging.LogFactory,java.util.logging.Logger" />
-      <option name="loggerFactoryMethodName" value="getLogger,getLogger,getLog,getLogger" />
-    </inspection_tool>
     <inspection_tool class="NullableProblems" enabled="false" level="WARNING" enabled_by_default="false">
       <option name="REPORT_NULLABLE_METHOD_OVERRIDES_NOTNULL" value="true" />
       <option name="REPORT_NOT_ANNOTATED_METHOD_OVERRIDES_NOTNULL" value="true" />
diff --git a/library/src/main/java/com/liulishuo/filedownloader/util/FileDownloadUtils.java b/library/src/main/java/com/liulishuo/filedownloader/util/FileDownloadUtils.java
index e42e26d5..9629ba49 100644
--- a/library/src/main/java/com/liulishuo/filedownloader/util/FileDownloadUtils.java
+++ b/library/src/main/java/com/liulishuo/filedownloader/util/FileDownloadUtils.java
@@ -283,6 +283,11 @@ public static boolean isDownloaderProcess(final Context context) {
             final ActivityManager activityManager = (ActivityManager) context.
                     getSystemService(Context.ACTIVITY_SERVICE);
 
+            if (activityManager == null) {
+                FileDownloadLog.w(FileDownloadUtils.class, "fail to get the activity manager!");
+                return false;
+            }
+
             final List<ActivityManager.RunningAppProcessInfo> runningAppProcessInfoList =
                     activityManager.getRunningAppProcesses();
 
@@ -466,6 +471,12 @@ public static String getThreadPoolName(String name) {
     public static boolean isNetworkNotOnWifiType() {
         final ConnectivityManager manager = (ConnectivityManager) FileDownloadHelper.getAppContext().
                 getSystemService(Context.CONNECTIVITY_SERVICE);
+
+        if (manager == null) {
+            FileDownloadLog.w(FileDownloadUtils.class, "failed to get connectivity manager!");
+            return true;
+        }
+
         final NetworkInfo info = manager.getActiveNetworkInfo();
 
         return info == null || info.getType() != ConnectivityManager.TYPE_WIFI;