嗯……

我认为你只是没有以正确的方式看待Android应用。你可以很容易地做一些你想做的事情:

像开发者生命周期文档中鼓励的那样，执行应用程序活动的保存/恢复状态。 如果在恢复阶段需要一些登录(没有可用的登录/会话信息)，那么就这样做。 最终添加一个按钮/菜单/超时，在这种情况下，你将执行finish()而不保存登录和其他会话信息，隐式地结束应用程序会话:因此，如果应用程序再次启动/带到前面，它将开始一个新的会话。

这样你就不关心应用是否真的从内存中删除了。

如果你真的想从内存中删除它(这是不鼓励的，顺便问一下，为了什么目的?)，你可以在onDestroy()的末尾有条件地杀死它，使用java.lang.System.exit(0)(或者restartPackage(..)?)当然，只有在你想“真正结束应用程序”的情况下才这样做，因为onDestroy()是活动正常生命周期的一部分，而不是应用程序的结束。

这很简单。只要遵循我要告诉你的这些指示:

比如你有多个活动，从一个活动到另一个活动。你可能会像这样使用intent:

Intent i1 = new Intent(this, AnotherActivity);
startActivity(i1) 

你只需要添加finish();例如，从头到尾在每个活动上启动intent活动后，

Intent i1=new Intent(this, AnotherActivity);
startActivity(i1) 
finish();

所以当你点击退出按钮时使用的是finish()或System.exit(0)必须完全关闭你的应用程序。

我同意泰德的观点。我明白退出应用程序不是 “Android方式”，但它似乎不应该被排除。在这里 您可能需要一个真正的应用程序出口(不是 只是活动):

The user might want some control over which app gets killed in the case of low memory. If important app A is running in the background, then you might like to exit app B when you are done with it so that app A doesn't get killed by the operating system. If your application has sensitive data cached in memory, you might like to kill the app so that a virus/worm/rogue app can't get at it. I know the security model is supposed to prevent that, but just in case... If your application uses resources (like network, CPU, sensors, etc.) that could adversely affect the phone, then one way of ensuring that those resources are freed up is to exit the application. I understand that well-behaved apps should free up resources when they are not needed. But again, exiting the application seems like a reasonable way of ensuring that.

如果你无法理解如何让你的数据/连接(因此你的“应用程序”)持久，那么你将无法用Android做你“需要”做的事情。

那些下载了这些可爱的小应用程序杀手的人通常会发现，它们对电池寿命或内存使用没有帮助，反而阻碍了操作系统有效管理内存的工作……

http://android-developers.blogspot.com/2010/04/multitasking-android-way.html

回答:(罗曼盖伊):用户不需要，系统会处理这个问题 自动。这就是活动生命周期(特别是 onPause/onStop/onDestroy)用于。无论你做什么，都不要放不下 “退出”或“退出”应用程序按钮。这在安卓系统中毫无用处 应用程序模型。这也与核心应用程序的方式相反 工作。

1: Totally exiting an application may be generally unmandatory, but it is not useless. What if windows had no exit option? System would be doggy slow as memory was full and the OS had to guess at which programs you were done with. I don't care what Romain Guy or even Larry Page and Sergey Brin say - these are unquestionable facts: Systems run slower when they have to kill tasks to get their memory before a new app can be launched. You just can't tell me that it doesn't take time to kill an app! Even the light from distant stars take time... There is some use in allowing the user to fully close apps.

2:与核心应用程序的工作方式相反?这是什么意思?当我现在运行一个应用程序时，它不再做任何工作……它只是在需要内存时等待被操作系统杀死。

总而言之，最小化和退出之间有明显的区别，两者都不适合对方。每个螺丝上都留个螺丝刀吗?还是每扇门都有钥匙?我们是不是把所有的电器都开着，直到断路器爆炸，我们需要打开另一个电器?我们是不是把洗碗机里装满了盘子，每次只拿出足够的空间来放一些新的脏盘子?我们把所有的车都停在车道上，直到——哦，算了。

如果用户想要最小化应用程序，那么最好的方法就是最小化它。如果用户想要退出应用程序，那么无论如何最好是退出。

这会让人皱眉吗?这是Android的观点——他们不赞成。许多独立的Android新手开发者对此表示不满。

但当它落到实处时，有好的编码和坏的编码。有好的程序流模型也有坏的程序流模型。

当用户知道他们已经用完了程序时，把程序留在内存中并不是好的程序流程。它完全没有任何用处，而且在启动新应用程序或运行应用程序分配更多内存时，它会减慢运行速度。

这有点像你的汽车:有时你让它一直开着，比如在红绿灯前停车，或者在快餐店经过时停车，或者在自动取款机前停车。但在其他情况下，你确实想把它关掉——比如当你去工作的时候，或者在杂货店，甚至在家里。

同样地，如果你正在玩游戏，这时手机响了。暂停游戏并继续运行。但如果用户已经玩了一段时间，那就让他们退出游戏吧。

The exit button on some applications should be more out in front than others. Games, for example, or programs where the user is likely to want to fully exit, should have an obvious exit. Other programs, like, perhaps, email programs, where exiting is an unlikely desire (so that it can keep checking for email) -- these programs should not waste prime control input screen space with an exit option, but for good program flow, it should have an exit option. What if someone decides they don't want their mail program trying to check email when they are in poor coverage area, or maybe in a Skype call or whatever? Let them exit the email program if they want!

暂停和退出是两项至关重要的任务，两者都不能实现对方的作用。

All of my applications have quit buttons... and I quite frequently get positive comments from users because of it. I don't care if the platform was designed in a fashion that applications shouldn't need them. Saying "don't put them there" is kind of ridiculous. If the user wants to quit... I provide them the access to do exactly that. I don't think it reduces how Android operates at all and seems like a good practice. I understand the life cycle... and my observation has been that Android doesn't do a good job at handling it.... and that is a basic fact.