Android 如何将应用程序对象放入片段类
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How to get application object into fragment class
提问by Rakesh Gourineni
I am changing my android mobile app to support both tablets and mobile phone. For this I am changing my activity class into fragment. In my activity class I have an instance of my application class created as below:
我正在更改我的 android 移动应用程序以支持平板电脑和手机。为此，我将我的活动类更改为片段。在我的活动类中，我创建了一个应用程序类的实例，如下所示：
appCtx = (UnityMobileApp) getApplication();
Where UnityMobileAppis my Application class.
UnityMobileApp我的应用程序类在哪里。
Now I want to create the same instance in my fragment class. Can you guys please help me solve this?
现在我想在我的片段类中创建相同的实例。大家能帮我解决这个问题吗？
回答by biegleux
Use appCtx = (UnityMobileApp) getActivity().getApplication();in your fragment.
appCtx = (UnityMobileApp) getActivity().getApplication();在您的片段中使用。
回答by BharathRao
The method getActivity()may have possibility to return null. This may crash your app.So it is safe to use that method inside the onActivityCreated(). Eg:
该方法getActivity()可能有可能返回 null。这可能会使您的应用程序崩溃。因此在onActivityCreated(). 例如：
private UnityMobileApp appCtx;
.
.
...
@Override
public View onCreateView(...){
...
}
@Override public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
appCtx = ((UnityMobileApp) getActivity().getApplication());
}
...
//access the application class methods using the object appCtx....
This answer is derived from Dzianis Yafima's answer asked by Ognyan in comments. Thus the Credit goes to Dzianis Yafima'sand Ognyanin stackoverflow.
该答案源自 Ognyan 在评论中提出的 Dzianis Yafima 的回答。因此，归功于stackoverflow 中的Dzianis Yafima和 Ognyan。
回答by Alex Nolasco
Alternatively using Kotlin
或者使用 Kotlin
fun bar() {
(activity?.application as UnityMobileApp).let {
it.drink()
} ?: run {
Log.d("DEBUG", "(╯°□°）╯︵ ┻━┻")
}
}
回答by Irony Stack
As you are trying yo use application context from fragment you can not use getApplication()because that isn't method of Fragment class
So you first have to use the getActivity()which will return a Fragment Activity to which the fragment is currently associated with.
当您尝试使用片段中的应用程序上下文时，您无法使用，getApplication()因为这不是 Fragment 类的方法
所以您首先必须使用getActivity()将返回片段当前关联的片段活动。
to sumup in your code,
总结一下你的代码，
instead of this.getApplication()you have to use getActivity.getApplication()
而不是this.getApplication()你必须使用getActivity.getApplication()
know more about getActivity()from android documentation
getActivity()从android 文档中了解更多信息
