context.getExternalFilesDir（空）为空 [英] context.getExternalFilesDir(null) is null

问题描述

我试图调试我在我的应用程序有问题。问题是，getExternalFiles（DIR）返回null在我的Andr​​oid应用程序，但我不知道为什么。我有必要的权限。这是存在于多种设备和Android版本（2.3.5及以上）的错误。让我知道如果你需要任何更多的信息。

I am trying to debug a problem I am having in my app. The issue is that getExternalFiles(dir) returns null in my android app but I am not sure why. I have the necessary permissions. This is a bug which exists on multiple devices and versions of android (2.3.5 and up). Let me know if you need any more information.

code的线，是问题是：

The line of code which is the problem is:

路径= context.getExternalFilesDir（空）+/database/mydata.db;

path = context.getExternalFilesDir(null) + "/database/mydata.db";

或

路径= context.getFilesDir（）getAbsolutePath（）+/database/mydata.db。

path = context.getFilesDir().getAbsolutePath() + "/database/mydata.db";

感谢您。

推荐答案

context.getExternalFilesDir（空）返回空是一个完全有效的响应。

context.getExternalFilesDir(null) returning null is a perfectly valid response.

从文档：

返回

在外部存储的目录控股应用程序文件的路径。返回空如果外部存储当前未安装，从而它不能保证路径存在;你将需要可用时再调用这个方法。

The path of the directory holding application files on external storage. Returns null if external storage is not currently mounted so it could not ensure the path exists; you will need to call this method again when it is available.

<一个href=\"http://developer.android.com/reference/android/content/Context.html#getExternalFilesDir(java.lang.String)\" rel=\"nofollow\">http://developer.android.com/reference/android/content/Context.html#getExternalFilesDir(java.lang.String)

所以看起来它失败有一个外接SD卡目前无法使用（用户安装它，删除它，等）的设备。

So it looks like the devices where it is failing have an external SD card that is currently not available (user has mounted it, removed it, etc.).

您必须检查这种情况下，使用类似 Environment.getExternalStorageState（）和相应的处理，如果它不存在。

You will have to check for this case using something like Environment.getExternalStorageState() and handle accordingly if it's not there.

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