My activity calls finish() (which doesn't make it finish immediately, but will do eventually) and calls Google Street Viewer. When I debug it on Eclipse, my connection to the app breaks when Street Viewer is called, which I understand as the (whole) application being closed, supposedly to free up memory (as a single activity being finished shouldn't cause this behavior). Nevertheless, I'm able to save state in a Bundle via onSaveInstanceState() and restore it in the onCreate() method of the next activity in the stack. Either by using a static singleton or subclassing Application I face the application closing and losing state (unless I save it in a Bundle). So from my experience they are the same with regards to state preservation. I noticed that the connection is lost in Android 4.1.2 and 4.2.2 but not on 4.0.7 or 3.2.4, which in my understanding suggests that the memory recovery mechanism has changed at some point.

My activity calls finish() (which doesn't make it finish immediately, but will do eventually) and calls Google Street Viewer. When I debug it on Eclipse, my connection to the app breaks when Street Viewer is called, which I understand as the (whole) application being closed, supposedly to free up memory (as a single activity being finished shouldn't cause this behavior). Nevertheless, I'm able to save state in a Bundle via onSaveInstanceState() and restore it in the onCreate() method of the next activity in the stack. Either by using a static singleton or subclassing Application I face the application closing and losing state (unless I save it in a Bundle). So from my experience they are the same with regards to state preservation. I noticed that the connection is lost in Android 4.1.2 and 4.2.2 but not on 4.0.7 or 3.2.4, which in my understanding suggests that the memory recovery mechanism has changed at some point.

它们实际上是一样的。 我能看出一点不同。使用Application类，你可以在Application. oncreate()中初始化你的变量，并在Application. onterminate()中销毁它们。对于单例，你必须依赖VM初始化和销毁静态数据。

我强烈推荐单身人士。如果你有一个需要context的单例，有:

MySingleton.getInstance(Context c) {
    //
    // ... needing to create ...
    sInstance = new MySingleton(c.getApplicationContext());
}

比起应用程序，我更喜欢单例，因为它有助于保持应用程序更有组织性和模块化——而不是在一个地方维护整个应用程序的所有全局状态，每个单独的部分都可以照顾自己。另外，单例会延迟初始化(在请求时)，而不是引导您在Application.onCreate()中预先进行所有初始化，这是很好的。

使用单例对象在本质上并没有错。只要在有意义的时候正确地使用它们。Android框架实际上有很多，用于维护加载资源的每个进程缓存和其他类似的东西。

同样，对于简单的应用程序，多线程不会成为单例的问题，因为根据设计，所有对应用程序的标准回调都在进程的主线程上分派，所以你不会发生多线程，除非你通过线程显式地引入它，或者通过将内容提供程序或服务IBinder隐式地发布给其他进程。

对你所做的事情要深思熟虑。：）

我也有同样的问题:单例还是做一个子类android.os.Application?

首先，我尝试了单例，但我的应用程序在某些时候会调用浏览器

Intent myIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.google.com"));

问题是，如果手机没有足够的内存，你的大多数类(甚至是单例)被清理以获得一些内存，当从浏览器返回到我的应用程序时，它每次都崩溃了。

解决方案:将需要的数据放在Application类的子类中。

来自:开发人员>参考-应用程序

通常不需要子类化Application。在大多数情况下， 静态单例可以以更模块化的方式提供相同的功能 道路如果你的单例需要一个全局上下文(例如注册 广播接收器)，检索它的函数可以给出一个 在内部使用Context. getapplicationcontext()时 首先构造单例。