Java 应用程序chrash:IlegalStateException错误

我收到以下错误：

Process: com.example.myweatherapp.myweatherapp, PID: 1263
    java.lang.IllegalStateException: Could not execute method of the activity
Caused by: android.os.NetworkOnMainThreadException

在尝试运行我的应用程序时。我的应用程序应该显示来自XML的数据。XML在web上，所以我必须首先通过将URL放入其中来获取它。在此之前，我会检查手机是否连接了互联网

If yes, then proceed with fetchXML and when done, store it also in /res/raw/dataxml . 
If not, then start handlingStoredXML (I have put the file in /res/raw/dataxml).

当我尝试运行应用程序时，它会死掉

main活动类：

11-12 13:04:09.538    1263-1263/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.myweatherapp.myweatherapp, PID: 1263
    java.lang.IllegalStateException: Could not execute method of the activity
            at android.view.View$1.onClick(View.java:4007)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.reflect.InvocationTargetException
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4002)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: android.os.NetworkOnMainThreadException
            at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)
            at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
            at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
            at java.net.InetAddress.getAllByName(InetAddress.java:215)
            at com.android.okhttp.HostResolver$1.getAllByName(HostResolver.java:29)
            at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:232)
            at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:124)
            at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:272)
            at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:211)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:373)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:106)
            at com.example.myweatherapp.myweatherapp.DownloadXML.fetchXML(DownloadXML.java:66)
            at com.example.myweatherapp.myweatherapp.HandleXML.handlingOnlineXML(HandleXML.java:55)
            at com.example.myweatherapp.myweatherapp.DownloadXML.checkInetConnection(DownloadXML.java:37)
            at com.example.myweatherapp.myweatherapp.MainActivity.ButtonClick(MainActivity.java:39)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4002)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

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下载XML类：

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对不起，我不知道任何其他来源，我可以很容易地存储我的代码和分享这里。但它太大了，不能复制到这里

希望有人能帮我。我在这里浏览了一下，发现了AsyncTask，但我不知道如何在代码中实现它

LOGCAT:

11-12 13:04:09.538    1263-1263/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.myweatherapp.myweatherapp, PID: 1263
    java.lang.IllegalStateException: Could not execute method of the activity
            at android.view.View$1.onClick(View.java:4007)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.reflect.InvocationTargetException
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4002)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: android.os.NetworkOnMainThreadException
            at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)
            at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
            at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
            at java.net.InetAddress.getAllByName(InetAddress.java:215)
            at com.android.okhttp.HostResolver$1.getAllByName(HostResolver.java:29)
            at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:232)
            at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:124)
            at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:272)
            at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:211)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:373)
            at com.android.okhttp.internal.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:106)
            at com.example.myweatherapp.myweatherapp.DownloadXML.fetchXML(DownloadXML.java:66)
            at com.example.myweatherapp.myweatherapp.HandleXML.handlingOnlineXML(HandleXML.java:55)
            at com.example.myweatherapp.myweatherapp.DownloadXML.checkInetConnection(DownloadXML.java:37)
            at com.example.myweatherapp.myweatherapp.MainActivity.ButtonClick(MainActivity.java:39)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4002)
            at android.view.View.performClick(View.java:4756)
            at android.view.View$PerformClick.run(View.java:19749)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

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谢谢@Ravi：是的，我读到了：[/link]，但是，我不知道如何在我的案例中使用它。您从我的代码中复制的部分位于

switch

case语句中-我不知道如何在这里实现异步。有什么帮助吗？把数据放在onPostExecute（）或runonuithread（）中都是一样的，你可以根据需要使用它。谢谢Ravi，我会测试你的答案！我现在得到了这个错误：

原因：java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“java.lang.String com.example.myweatherapp.myweatherapp.HandleXML.getTemperature（）”

行：OnPostExecuter请稍后阅读注释。我会接受你的回答，因为它现在起作用了！非常感谢拉维！

case R.id.btn_search:
             new LoadData().execute();
              break;