情况如下：
学习Facebook的ReactNative，将js代码加入到已有的Android代码中。使用AndroidStudio编辑，报错如下：
E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
at java.util.concurrent.FutureTask.run(FutureTask.java:239)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
Caused by: java.lang.IllegalAccessError: tried to access method android.support.v4.net.ConnectivityManagerCompat.<init>:(Lcom/facebook/react/bridge/ReactApplicationContext;)V
from class com.facebook.react.modules.netinfo.NetInfoModule
at com.facebook.react.modules.netinfo.NetInfoModule.<init>(NetInfoModule.java:55)
at com.facebook.react.shell.MainReactPackage.createNativeModules(MainReactPackage.java:67)
at com.facebook.react.ReactInstanceManagerImpl.processPackage(ReactInstanceManagerImpl.java:793)
at com.facebook.react.ReactInstanceManagerImpl.createReactContext(ReactInstanceManagerImpl.java:730)
at com.facebook.react.ReactInstanceManagerImpl.access$600(ReactInstanceManagerImpl.java:91)
at com.facebook.react.ReactInstanceManagerImpl$ReactContextInitAsyncTask.doInBackground(ReactInstanceManagerImpl.java:184)
at com.facebook.react.ReactInstanceManagerImpl$ReactContextInitAsyncTask.doInBackground(ReactInstanceManagerImpl.java:169)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask.run(FutureTask.java:234)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
原因是Android support v7有些版本会与ReactNative包冲突，一开始使用的是
compile 'com.android.support:appcompat-v7:23.2.1' compile 'com.facebook.react:react-native:0.20.+'都是最新的版本，但是相互冲突，后来更改为
compile 'com.android.support:appcompat-v7:23.1.+' compile 'com.facebook.react:react-native:0.20.+'问题不在出现。