blocks|key|326041|text|实际上，一次运行的活动永远不会超过一个。解决这个问题的简单方法是让第一个活动在启动第二个活动之前关闭它的连接。您可以在onPause()中执行此操作，然后在onResume()中重新打开它。如下所示(非常psuedo-code)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|326042|MyActivity+{
++++OnResume()
++++++++open+connection+to+database
++++OnPause()
++++++++close+connection+to+database
}|code-block|syntax|javascript|326043|通过这种方式，您永远不会尝试一次拥有多个连接，并且该连接始终可用。|326044|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

There's never really more than one Activity running at a time. The easy way to fix this would be to have the first Activity close it's connection before starting the second Activity. You can do this in the onPause() then reopen it in the onResume(). Something like this (very psuedo-code):

<pre><code>MyActivity {
 OnResume()
 open connection to database
 OnPause()
 close connection to database
}
</code></pre>

This way you're never trying to have more than one connection at a time and the connection is always available.

blocks|key|3084321|text|我还有多个活动，每个活动都打开自己的数据库连接。当我启动其他活动时，我会保持主活动处于活动状态，并且当我不再需要子活动时，我会对子活动调用finish()。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084322|我所看到的是，子活动可以成功地打开连接并查询数据，而主活动仍然持有它的DBAdapter。当子活动结束时，主活动将重新查询所有打开的游标。这似乎是自动发生的。|3084323|然而，在用户界面上单击了一段时间后，我的应用程序开始和结束活动，我最终会得到一个异常：|3084324|ERROR/Database(17657):+Leak+found
ERROR/Database(17657):+java.lang.IllegalStateException:
++++++/data/data/yourpackage/databases/yourdatabase+
++++++SQLiteDatabase+created+and+never+closed
ERROR/Database(17657):+at+android.database.sqlite.SQLiteDatabase.<init>
+++++(SQLiteDatabase.java:1694)|code-block|syntax|javascript|3084325|异常不是来自当前在前台的活动，而是来自不久前完成的活动。因此，垃圾收集器正在清理并找到打开的数据库连接。这不会影响应用程序-它继续正常工作，并且来自前台活动的所有查询都会返回数据。|3084326|解决方案只是关闭子活动中的连接。onDestroy()事件是执行此操作的正确位置：|3084327|@Override++++
protected+void+onDestroy()+{++++++++
++++super.onDestroy();
++++myAdapter.close();
}|3084328|因为我把它放在我所有的孩子活动中，我不再得到异常。|3084329|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|H|7|10|8|@]|9|@]|A|$I|J]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

I also have multiple Activities and each Activity opens its own database connection. I keep the main Activity alive while I start other activities, and I call finish() on the child activities when I no longer need them.

What I am seeing is that a child Activity can successfully open a connection and query data while the main Actitity is still holding on to its DBAdapter. When the child Activity ends, the main Activity requeries any cursors that are open. This seems to happen automatically.

However, after clicking around on the user interface for a while, which causes my app to start and finish Activities, I will eventually get the exception:

<pre><code>ERROR/Database(17657): Leak found
ERROR/Database(17657): java.lang.IllegalStateException:
 /data/data/yourpackage/databases/yourdatabase 
 SQLiteDatabase created and never closed
ERROR/Database(17657): at android.database.sqlite.SQLiteDatabase.&lt;init&gt;
 (SQLiteDatabase.java:1694)
</code></pre>

The exception is not from the Activity that is currently in the foreground, but from one that was finished a while ago. So, what happens is that the garbage collector is cleaning up and finding the open database connection. This does not affect the app - it continues to work fine and all queries from the foreground Activity return data.

The solution is simply to close the connection in the child Activity. The onDestroy() event is the right place to do that:

<pre><code>@Override 
protected void onDestroy() { 
 super.onDestroy();
 myAdapter.close();
}
</code></pre>

Since I put this in all my child Activities, I no longer get the exception.

blocks|key|326057|text|我要做的是在一个超类中定义数据库，如果所有的活动都扩展了这个类，那么这个超类就是AppCompatActivity，或者在所有活动继承的Activity类中定义它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|326058|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

What I would do is define the database in a superclass which is AppCompatActivity if all the activities extend this class, or define it in Activity class which is inherited for all activities.

Can two or more Android Activities open an sqlite3 database for write? 

I have two Activities that need to insert data into the same sqlite database. When the second Activity calls <code>SQLiteOpenHelper.getWriteableDatabase()</code> an IllegalStateException is thrown with the message "SQLiteDatabase created and never closed". 

I've been able to avoid the Exception by making my database object a singleton but I'm thinking there must be a better way. 

Thanks,

John

Sharing sqlite database between multiple Android Activities

数据库

Android

两个或更多的Android活动可以打开sqlite3数据库进行写操作吗？我有两个活动需要将数据插入到同一个sqlite数据库中。当第二个活动调用SQLiteOpenHelper.getWriteableDatabase()时，会抛出一个IllegalStateException，并显示消息"SQLiteDatabase...

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