如何查询堆栈中的活动? [英] How do I query the activities on the stack?

问题描述

我有一个编辑联系人项目的活动.除了可以在应用程序内通过导航调用之外，我还有一个主屏幕快捷键，可用于EditItem活动.

I have an activity that edits a contact item. As well as being invoked by navigation within the app, I have a home screen shortcut to the EditItem activity.

我的问题是，潜在的用户可能正在编辑联系人，忘记了他正在这样做，然后通过快捷方式重新编辑了该联系人，即，堆栈上可能有两个EditItem活动.如果发生这种情况，则其中一个进行的编辑会破坏另一个.

My problem is that potentially a user could be editing a contact, forget that he was doing so, and re-edit the contact via the shortcut, ie there could be two EditItem activities on the stack. If this happens, edits from one will clobber the other.

我如何检测和/或避免这种情况?

How do I detect and/or avoid this scenario?

推荐答案

只需在 AndroidManifest.xml 文件中将您的编辑活动标记为"singleTask":

Just mark your edit activity as a "singleTask" in your AndroidManifest.xml file:

<activity
    android:name=".EditActivity"
    android:label="@string/app_name"
    android:launchMode="singleTask" />

您可以在launchMode 模式下进行阅读="nofollow"> Android开发人员指南.要引用它，

You can read up on the launchMode mode in the Android Developer Guide. To quote it,

系统在新任务的根部创建活动并进行路由目的.但是，如果该活动的实例已经存在存在，系统通过以下方式将意图路由到现有实例调用其onNewIntent()方法，而不是创建一个新方法.

The system creates the activity at the root of a new task and routes the intent to it. However, if an instance of the activity already exists, the system routes the intent to existing instance through a call to its onNewIntent() method, rather than creating a new one.

例如，我已经将此模式用于地图活动，这可能会导致活动堆栈中的循环.为了避免用户执行活动A-> B-> C-> B-> C，然后必须将所有活动都按Back，我将活动C设置为"singleTask".这样，用户只需在活动B中按一次返回"即可到达活动A.

For instance, I've used this mode for a map activity that could cause cycles in the activity stack. To avoid a user doing activity A -> B -> C -> B -> C and then having to press Back through all of them, I made activity C a "singleTask". That way the user only ever had to press Back once from activity B to reach activity A.

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