此时我非常沮丧。我已经研究了几天，甚至无法隔离任何超出游标问题的东西。我正在扩展ListActivity并在OnCreate方法中使用startManagingCursor（newcursor）。这是在按下主页按钮时运行和崩溃的代码（数据库已经填满）：
private void loadAlbums() {
try {
newcursor = mDbHelper.getAlbumTitlesCursor();
dbalbumadapter = new AlbumListCursorAdapter(this, newcursor);
setListAdapter(dbalbumadapter);
}
catch (SQLiteException s) {
newcursor = null;
fetchalbums = new FetchAlbumsTask().execute();
}
current_view = ALBUMTITLE_VIEW;
}
以下是错误日志：
02-03 13:41:42.379: WARN/dalvikvm(340): threadid=3: thread exiting with uncaught exception (group=0x4001b188)
02-03 13:41:42.389: ERROR/AndroidRuntime(340): Uncaught handler: thread main exiting due to uncaught exception
02-03 13:41:42.590: ERROR/AndroidRuntime(340): java.lang.RuntimeException: Unable to stop activity {com.skip.ngRCv2/com.skip.ngRCv2.ngRC}: java.lang.RuntimeException: Unable to stop activity {com.skip.ngRCv2/com.skip.ngRCv2.MusicLibraryActivity}: java.lang.NullPointerException
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3227)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.handleStopActivity(ActivityThread.java:3272)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.access$2500(ActivityThread.java:119)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1880)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.os.Handler.dispatchMessage(Handler.java:99)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.os.Looper.loop(Looper.java:123)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.main(ActivityThread.java:4363)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at java.lang.reflect.Method.invokeNative(Native Method)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at java.lang.reflect.Method.invoke(Method.java:521)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at dalvik.system.NativeStart.main(Native Method) 02-03 13:41:42.590: ERROR/AndroidRuntime(340):
Caused by: java.lang.RuntimeException: Unable to stop activity {com.skip.ngRCv2/com.skip.ngRCv2.MusicLibraryActivity}: java.lang.NullPointerException
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3227)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.performStopActivity(ActivityThread.java:3174)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:176)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.LocalActivityManager.dispatchStop(LocalActivityManager.java:572)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityGroup.onStop(ActivityGroup.java:79)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.Instrumentation.callActivityOnStop(Instrumentation.java:1169)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.Activity.performStop(Activity.java:3797)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3224)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): ... 11 more
02-03 13:41:42.590: ERROR/AndroidRuntime(340):
Caused by: java.lang.NullPointerException
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.Activity.performStop(Activity.java:3808)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3224)
02-03 13:41:42.590: ERROR/AndroidRuntime(340): ... 18 more
在Activity.performStop（Activity.java:3808）上有一个NullPointerException，它似乎来自Activity.java中的这个方法，即使我无法用行号交叉验证：
final void performStop() {
if (!mStopped) {
if (mWindow != null) {
mWindow.closeAllPanels();
}
mCalled = false;
mInstrumentation.callActivityOnStop(this);
if (!mCalled) {
throw new SuperNotCalledException(
"Activity " + mComponent.toShortString() +
" did not call through to super.onStop()");
}
synchronized (mManagedCursors) {
final int N = mManagedCursors.size();
for (int i=; i<N; i++) {
ManagedCursor mc = mManagedCursors.get(i);
if (!mc.mReleased) {
mc.mCursor.deactivate();
mc.mReleased = true;
}
}
}
mStopped = true;
}
mResumed = false;
}
我尝试在OnStop方法中关闭和停用光标，并将列表适配器设置为null。我的印象是，当我按照指示让活动管理光标时，这一切都不是必需的。我将光标传递给我的自定义适配器，但我发现的任何示例都没有在适配器内进行任何管理。
如果你能帮助我至少缩小抛出这个例外的内容，我将不胜感激！
答案 0 :(得分：9)
如果这是正确的转速，则行3808对应于：
[[我知道它不是官方的android源码，但行号排列]]
mc.mCursor.deactivate();
据我所知，mc永远不会为空。 只有当mCursor光标传递到null时，null（最后的）似乎才是startManagingCursor()。 我之前抓住了我的笔记，让其他人确认了这一点。
您可以在将光标传递到startManagingCursor()之前将光标记录下来吗？ 我很好奇崩溃前最后一次出现的消息说。
当出现sql异常时，你有这一行：
newcursor = null;
我想知道这是否正在进入startManagingCursor()电话。
注意：
ManagedCursor：public void startManagingCursor(Cursor c) {
synchronized (mManagedCursors) {
mManagedCursors.add(new ManagedCursor(c));
}
}
ManagedCursor设置final字段mCursor：private static final class ManagedCursor {
ManagedCursor(Cursor cursor) {
mCursor = cursor;
mReleased = false;
mUpdated = false;
}
private final Cursor mCursor;
private boolean mReleased;
private boolean mUpdated;
}
startManagingCursor()的所有内部呼叫都受到保护，例如：if (c != null) {
startManagingCursor(c);
}
return c;
答案 1 :(得分：0)
在调试器中启动你的应用程序，在NPE上设置一个异常断点，然后看看它在哪里拯救。
应该让你知道发生了什么。