我正在构建一个Android应用程序，其活动包含以下代码：
public class SavedSalesActivity extends Activity {
protected ListView mSalesList;
protected Cursor mSalesCursor;
protected SalesCursorAdapter mSalesAdapter;
protected SalesDbAdapter mDb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sales_list);
mDb = new SalesDbAdapter(this);
mDb.open();
mSalesCursor = mDb.getSaved();
startManagingCursor(mSalesCursor);
mSalesAdapter = new SalesCursorAdapter(this, R.layout.sales_list_item, mSalesCursor,
new String[0], new int[0]);
mSalesList = (ListView)findViewById(R.id.sales_listview);
mSalesList.setAdapter(mSalesAdapter);
mSalesList.setEmptyView(findViewById(android.R.id.empty));
mSalesList.setOnItemClickListener(new OnItemClickListener() {...});
}
@Override
protected void onStart() {
Log.v(TAG, "Starting SavedSalesActivity");
mDb.open();
mSalesCursor = mDb.getSaved();
startManagingCursor(mSalesCursor);
super.onStart();
}
@Override
protected void onStop() {
Log.v(TAG, "Stopping SavedSalesActivity");
mSalesCursor.close();
mDb.close();
super.onStop();
}
}
根据我的理解，这应该足以正确关闭我的所有资源，但是如果我打开此活动并使用Android设备退出按钮退出，我会在短暂（可变）时间段后在Logcat中得到此信息。
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): Releasing statement in a finalizer. Please ensure that you explicitly call close() on your cursor: SELECT * FROM sales ORDER BY featured DESC
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:62)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:80)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:46)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:42)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1345)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1229)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1184)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1264)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at com.maps.app.classifiedconcepts.sale.SalesDbAdapter.getSaved(SalesDbAdapter.java:149)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at com.maps.app.classifiedconcepts.sale.SavedSalesActivity.onCreate(SavedSalesActivity.java:113)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.os.Looper.loop(Looper.java:123)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at java.lang.reflect.Method.invokeNative(Native Method)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at java.lang.reflect.Method.invoke(Method.java:521)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-08 19:33:58.492: WARN/SQLiteCompiledSql(5169): at dalvik.system.NativeStart.main(Native Method)
03-08 19:33:58.503: ERROR/Database(5169): close() was never explicitly called on database '/data/data/com.maps.app.classifiedconcepts/databases/classified_concepts'
03-08 19:33:58.503: ERROR/Database(5169): android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
03-08 19:33:58.503: ERROR/Database(5169): at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1810)
03-08 19:33:58.503: ERROR/Database(5169): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:817)
03-08 19:33:58.503: ERROR/Database(5169): at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:851)
03-08 19:33:58.503: ERROR/Database(5169): at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:844)
03-08 19:33:58.503: ERROR/Database(5169): at android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:540)
03-08 19:33:58.503: ERROR/Database(5169): at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)
03-08 19:33:58.503: ERROR/Database(5169): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:112)
03-08 19:33:58.503: ERROR/Database(5169): at com.maps.app.classifiedconcepts.sale.SalesDbAdapter.open(SalesDbAdapter.java:163)
03-08 19:33:58.503: ERROR/Database(5169): at com.maps.app.classifiedconcepts.sale.SavedSalesActivity.onCreate(SavedSalesActivity.java:112)
03-08 19:33:58.503: ERROR/Database(5169): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-08 19:33:58.503: ERROR/Database(5169): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
03-08 19:33:58.503: ERROR/Database(5169): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
03-08 19:33:58.503: ERROR/Database(5169): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
03-08 19:33:58.503: ERROR/Database(5169): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
03-08 19:33:58.503: ERROR/Database(5169): at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 19:33:58.503: ERROR/Database(5169): at android.os.Looper.loop(Looper.java:123)
03-08 19:33:58.503: ERROR/Database(5169): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-08 19:33:58.503: ERROR/Database(5169): at java.lang.reflect.Method.invokeNative(Native Method)
03-08 19:33:58.503: ERROR/Database(5169): at java.lang.reflect.Method.invoke(Method.java:521)
03-08 19:33:58.503: ERROR/Database(5169): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-08 19:33:58.503: ERROR/Database(5169): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-08 19:33:58.503: ERROR/Database(5169): at dalvik.system.NativeStart.main(Native Method)
mSalesCursor = mDb.getSaved（）; 行在我的SalesDbAdapter中调用以下代码：
public Cursor getSaved() {
return mDb.query(TABLE_NAME, null, null, null, null, null, KEY_FEATURED + " DESC");
}
我做错了什么？为什么我会收到这些例外？我特别困惑，因为我认为在初始化mSalesCursor之后立即调用startManagingCursor（mSalesCursor）可以避免在任何Activity Lifecycle方法中关闭Cursor的需要。
答案 0 :(得分：2)
对于其他人来看这个答案，我总是用try / catch / finally语句包装我的Cursor用法。无论发生什么情况，这都可以确保光标关闭。
我经常使用它，甚至我做了一个Eclipse模板。
示例：
void foo() {
Cursor c = null;
try {
c = db.get_somthing();
do_something©;
}
catch (Exception e) {
print_err_msg(e);
}
finally {
if (c != null) {
c.close();
c = null;
}
}
}
答案 1 :(得分：0)
对于这些类型的事情，您应该覆盖onResume()和onPause()而不是onStart()和onStop()。查看Activity Lifecycle文档。
答案 2 :(得分：0)