在Android上的数据库安装期间使用AsyncTask与Sqlite崩溃的应用程序？
我正在尝试使用以下代码安装相当大的数据库的AsyncTask：
package samples.employeedirectory; import android.app.ListActivity; import android.app.ProgressDialog; import android.content.Context; import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.os.AsyncTask; import android.os.Bundle; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.WindowManager; import android.widget.ListAdapter; import android.widget.ListView; public class EmployeeList extends ListActivity { protected SQLiteDatabase db; protected Cursor cursor; protected ListAdapter adapter; protected Context context; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); grabURL(); } public void grabURL() { new GrabURL().execute(); } public void onListItemClick(ListView parent, View view, int position, long id) { Intent intent = new Intent(this, displayE.class); Cursor cursor = (Cursor) adapter.getItem(position); intent.putExtra("eID", cursor.getInt(cursor.getColumnIndex("eID"))); startActivity(intent); } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.menu, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.pref: // Launch Preference activity Intent intent = new Intent(this, Preferences.class); startActivity(intent); break; } return true; } private class GrabURL extends AsyncTask { private ProgressDialog Dialog = new ProgressDialog(EmployeeList.this); protected void onPreExecute() { Dialog.setMessage("Downloading source.."); Dialog.show(); } protected Void doInBackground(Object ... string) { db = (new DatabaseHelper(EmployeeList.this)).getWritableDatabase(); cursor = db.rawQuery("SELECT * FROM employee", new String[]{}); return null; } protected void onPostExecute(Void unused) { adapter = new qCursorAdapter(EmployeeList.this, cursor); Dialog.dismiss(); setListAdapter(adapter); } } } 这是应用程序的主要活动，问题是每次我第一次运行时应用程序崩溃。 我不知道为什么，但这是我得到的信息。
08-16 01:07:27.783: ERROR/WindowManager(8908): android.view.WindowLeaked: Activity samples.employeedirectory.EmployeeList has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@2afd0298 that was originally added here
关于SO的讨论这个错误有很多主题，但我无法完全理解它们与这个特定情况的关系。
编辑：
08-16 01:24:31.073: ERROR/AndroidRuntime(8995): FATAL EXCEPTION: AsyncTask #1 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): java.lang.RuntimeException: An error occured while executing doInBackground() 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.os.AsyncTask$3.done(AsyncTask.java:200) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.util.concurrent.FutureTask.setException(FutureTask.java:125) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.util.concurrent.FutureTask.run(FutureTask.java:138) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.lang.Thread.run(Thread.java:1019) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.os.Handler.(Handler.java:121) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.widget.Toast.(Toast.java:68) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.widget.Toast.makeText(Toast.java:231) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at samples.employeedirectory.DatabaseHelper.onCreate(DatabaseHelper.java:42) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:126) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at samples.employeedirectory.EmployeeList$GrabURL.doInBackground(EmployeeList.java:79) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at samples.employeedirectory.EmployeeList$GrabURL.doInBackground(EmployeeList.java:1) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.os.AsyncTask$2.call(AsyncTask.java:185) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): ... 4 more 08-16 01:24:31.083: ERROR/WindowManager(8995): Activity samples.employeedirectory.EmployeeList has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@2afd1760 that was originally added here 08-16 01:24:31.083: ERROR/WindowManager(8995): android.view.WindowLeaked: Activity samples.employeedirectory.EmployeeList has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@2afd1760 that was originally added here 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.view.ViewRoot.(ViewRoot.java:265) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.view.Window$LocalWindowManager.addView(Window.java:424) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.app.Dialog.show(Dialog.java:241) 08-16 01:24:31.083: ERROR/WindowManager(8995): at samples.employeedirectory.EmployeeList$GrabURL.onPreExecute(EmployeeList.java:75) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.os.AsyncTask.execute(AsyncTask.java:391) 08-16 01:24:31.083: ERROR/WindowManager(8995): at samples.employeedirectory.EmployeeList.grabURL(EmployeeList.java:40) 08-16 01:24:31.083: ERROR/WindowManager(8995): at samples.employeedirectory.EmployeeList.onCreate(EmployeeList.java:30) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1623) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.app.ActivityThread.access$1500(ActivityThread.java:121) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:943) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.os.Handler.dispatchMessage(Handler.java:99) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.os.Looper.loop(Looper.java:123) 08-16 01:24:31.083: ERROR/WindowManager(8995): at android.app.ActivityThread.main(ActivityThread.java:3701) 08-16 01:24:31.083: ERROR/WindowManager(8995): at java.lang.reflect.Method.invokeNative(Native Method) 08-16 01:24:31.083: ERROR/WindowManager(8995): at java.lang.reflect.Method.invoke(Method.java:507) 08-16 01:24:31.083: ERROR/WindowManager(8995): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:862) 08-16 01:24:31.083: ERROR/WindowManager(8995): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620) 08-16 01:24:31.083: ERROR/WindowManager(8995): at dalvik.system.NativeStart.main(Native Method)
问题出在您的DatabaseHelper的onCreate方法中，您尝试在UI线程外部显示Toast （它正在doInBackground中执行）。
你可以在这里发现：
08-16 01:24:31.073: ERROR/AndroidRuntime(8995): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.os.Handler.(Handler.java:121) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.widget.Toast. (Toast.java:68) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at android.widget.Toast.makeText(Toast.java:231) 08-16 01:24:31.073: ERROR/AndroidRuntime(8995): at samples.employeedirectory.DatabaseHelper.onCreate(DatabaseHelper.java:42)
我想您正在尝试通过设置适配器来更新onPostExecute中的Ui。 所以，为了做到这一点你已经使用了一个线程，所以试试这个。
EmployeeList.this.runOnUiThread(new Runnable() { @Override public void run() { setListAdapter(adapter); } });
如果您尝试更新UI外部的任何内容，请使用runOnUiThread进行更新。