Android的动作条上按钮对系统后退按钮 [英] Android Actionbar Up button versus system Back button

问题描述

我使用的动作条和它的向上按钮，从一个细节的活动返回到主活动，工作正常。同样，用户可以preSS系统的后退按钮返回到主活动。

I'm using the Actionbar and it's "up" button to return from a detail activity to the main activity, which works fine. Similarly, the user can press the system "back" button to return to the main activity.

在我的主要活动，在的onCreate（）数据从互联网上下载，显示在应用程序启动。我注意到，当我使用的动作条向上按钮，从细节到主要活动，的onCreate（）运行，重新下载数据。但的onCreate（）当我使用系统的后退按钮，所以立即显示出的主要活动视图不运行。

In my main activity, in onCreate() data is downloaded from the internet to display upon app start. I noticed that when I use the Actionbar "up" button to go from detail to main activity, onCreate() is run, re-downloading the data. But onCreate() is not run when I use the system "back" button, therefore immediately showing the main activity view.

在code我在细节活动使用来实现向上按钮：

The code I use in the detail activity to implement the "up" button is:

switch (item.getItemId()) {
   case android.R.id.home:
      Intent intent = new Intent(this, MainActivity.class);
      intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
      startActivity(intent);
      return true;

我想向上按钮的行为类似于后退按钮，而不是重新运行的onCreate（）。但我知道如何做到这一点，或者code路径中的后退按钮工具，返回的主要活动。

I would like the "up" button to behave like the "back" button and not rerun onCreate(). But I'm unsure how to make this happen, or which code path the "back" button implements to return to the main activity.

谢谢！

推荐答案

而不是开始一个全新的活动只是完成细节的活性你在

Instead of starting a whole new activity simply finish the details activity you are in

switch (item.getItemId()) {
   case android.R.id.home:
      finish();
      return true;

然后你将返回到上的活动堆栈中的previous活动（你的主要活动）和的onCreate不应该叫

Then you will return to the previous activity on the activity stack (your main activity) and onCreate shouldn't be called

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