4
最近我開始使用AsyncTask，發現使用它的一些問題。重新打開活動時出現AsyncTask（doInBackground方法）問題
我有這ListActivity（CatalogActivity），我用AsyncTask重新加載它，因爲它是某種樹的邏輯。每次我在列表中選擇一個項目時，我會進行一些計算並在doInBackground方法中顯示進度對話框，而在onPostExecute中，我重新加載列表並取消進度。一切正常。
im完成後（我達到最後一級），我開始另一個活動（LoginActivity）。這個新的活動有「後退」菜單按鈕，開始我以前提到的列表活動。它開始活動，當我點擊doInBackground方法的負載部分時，我得到這個時髦的例外。真正有趣的部分是，如果我在我的加載方法上設置斷點，並逐步完成所有工作！
我錯過了什麼？
這裏是我的CatalogActivity的doInBackground方法（如錯誤發生）：
protected String doInBackground(String... params) {
catalogAdapter.mappingServicesCatalog.loadFromRml(new RIoConnectionManagerImpl(currentActivity.getApplicationContext()), params[0], null, 120000, 500000);
if (catalogAdapter.urlMapping.size() == 0)
{
catalogAdapter.urlMapping.add(params[0]);
}
else
{
if (catalogAdapter.urlMapping.get(catalogAdapter.urlMapping.size() - 1) != params[0])
{
catalogAdapter.urlMapping.add(params[0]);
}
}
return "";
}
這裏是logcat的記錄：
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): FATAL EXCEPTION: AsyncTask #4
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): java.lang.RuntimeException: An error occured while executing doInBackground()
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at android.os.AsyncTask$3.done(AsyncTask.java:200)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.lang.Thread.run(Thread.java:1096)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): Caused by: java.lang.NullPointerException
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at si.realis.rmap.android.CatalogActivity$CatalogAdapter.access$1(CatalogActivity.java:35)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at si.realis.rmap.android.CatalogActivity$LoadRMLCatalog.doInBackground(CatalogActivity.java:197)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at si.realis.rmap.android.CatalogActivity$LoadRMLCatalog.doInBackground(CatalogActivity.java:1)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at android.os.AsyncTask$2.call(AsyncTask.java:185)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
06-20 11:38:21.109: ERROR/AndroidRuntime(22789): ... 4 more
06-20 11:38:44.086: ERROR/WindowManager(22789): Activity si.realis.rmap.android.CatalogActivity has leaked window [email protected] that was originally added here
06-20 11:38:44.086: ERROR/WindowManager(22789): android.view.WindowLeaked: Activity si.realis.rmap.android.CatalogActivity has leaked window [email protected] that was originally added here
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.view.ViewRoot.<init>(ViewRoot.java:247)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.view.Window$LocalWindowManager.addView(Window.java:424)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.Dialog.show(Dialog.java:241)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.ProgressDialog.show(ProgressDialog.java:107)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.ProgressDialog.show(ProgressDialog.java:90)
06-20 11:38:44.086: ERROR/WindowManager(22789): at si.realis.rmap.android.CatalogActivity.loadRMLCatalog(CatalogActivity.java:135)
06-20 11:38:44.086: ERROR/WindowManager(22789): at si.realis.rmap.android.CatalogActivity$CatalogAdapter.Initialize(CatalogActivity.java:60)
06-20 11:38:44.086: ERROR/WindowManager(22789): at si.realis.rmap.android.CatalogActivity$CatalogAdapter.<init>(CatalogActivity.java:45)
06-20 11:38:44.086: ERROR/WindowManager(22789): at si.realis.rmap.android.CatalogActivity.onCreate(CatalogActivity.java:119)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.os.Handler.dispatchMessage(Handler.java:99)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.os.Looper.loop(Looper.java:123)
06-20 11:38:44.086: ERROR/WindowManager(22789): at android.app.ActivityThread.main(ActivityThread.java:4627)
06-20 11:38:44.086: ERROR/WindowManager(22789): at java.lang.reflect.Method.invokeNative(Native Method)
06-20 11:38:44.086: ERROR/WindowManager(22789): at java.lang.reflect.Method.invoke(Method.java:521)
06-20 11:38:44.086: ERROR/WindowManager(22789): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:871)
06-20 11:38:44.086: ERROR/WindowManager(22789): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:629)
06-20 11:38:44.086: ERROR/WindowManager(22789): at dalvik.system.NativeStart.main(Native Method)
06-20 11:49:00.402: ERROR/WifiManager(22835): showApDialog
06-20 11:49:04.699: ERROR/HierarchicalStateMachine(2475): TetherMaster - unhandledMessage: msg.what=3
06-20 11:49:07.511: ERROR/WifiManager(22835): showApDialog
06-20 11:49:14.648: ERROR/WifiManager(22835): showApDialog
06-20 11:49:23.109: ERROR/libnetutils(2475): dhcp start cmd 11 : [dhcpcd:-ABK]
06-20 11:49:23.597: ERROR/HierarchicalStateMachine(2475): TetherMaster - unhandledMessage: msg.what=3
06-20 11:49:23.965: ERROR/gps_BRCM(2475): BrcmLbs_sync() return error.
需要在你的代碼摘要中的行號，以便與NPE stacktrace對齊：si.realis.rmap.android.CatalogActivity $ CatalogAdapter.access $ 1（CatalogActivity.java:35） - 哪一行我你的片段是第35行嗎？ '.access $ 1（）'意味着它使用合成訪問器方法請求私有成員，並且該成員看起來爲空。你說它「開始」前一個活動，但爲什麼不只是讓BACK鍵完成它，並完成最高活動，恢復以前的活動？ – Joe
你是對的。典型的noob錯誤。我有活動和一個適配器。在適配器構造函數中，我有一些代碼啓動了這個異步任務。當我調試適配器同步，但在運行時有錯誤。我從方法中的適配器構造函數中刪除了代碼，並且它可以工作。感謝您的時間 ！馬虎在我身邊工作... – no9