简单和简单的方法退出应用程序

Intent homeIntent = new Intent(Intent.ACTION_MAIN);
homeIntent.addCategory(Intent.CATEGORY_HOME);
homeIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(homeIntent);

这将杀死任何东西;)

int p = android.os.Process.myPid();
android.os.Process.killProcess(p);

你可以使用API 21中的finishAndRemoveTask ()

finishAndRemoveTask () 完成此任务中的所有活动，并将其从最近任务列表中移除。

如果您确实需要关闭应用程序，请认真考虑一下:为什么不让操作系统自行决定何时何地释放资源呢?

否则，如果你非常确定，就用

finish();

作为对@dave appleton评论的回应:第一件事是阅读大问题/答案组合@gabriel的帖子:退出应用程序是不受欢迎的吗?

现在假设我们有了这个，这里的问题仍然有一个答案，如果你要做任何关于退出的事情，你需要的代码是finish()。显然你可以有不止一项活动等等，但这不是重点。让我们看一些用例

You want to let the user quit everything because of memory usage and "not running in the background? Doubtfull. Let the user stop certain activities in the background, but let the OS kill any unneeded recourses. You want a user to not go to the previous activity of your app? Well, either configure it so it doesn't, or you need an extra option. If most of the time the back=previous-activity works, wouldn't the user just press home if he/she wants to do something else? If you need some sort of reset, you can find out if/how/etc your application was quit, and if your activity gets focus again you can take action on that, showing a fresh screen instead of restarting where you were.

所以最后，当然，finish()不会杀死所有东西，但我认为它仍然是你需要的工具。如果有“杀死所有活动”的用例，我还没有找到。

从API 16开始，你可以使用finishAffinity方法，它似乎非常接近于通过它的名称和Javadoc描述关闭所有相关的活动:

this.finishAffinity();

Finish this activity as well as all activities immediately below it in the current task that have the same affinity. This is typically used when an application can be launched on to another task (such as from an ACTION_VIEW of a content type it understands) and the user has used the up navigation to switch out of the current task and into its own task. In this case, if the user has navigated down into any other activities of the second application, all of those should be removed from the original task as part of the task switch. Note that this finish does not allow you to deliver results to the previous activity, and an exception will be thrown if you are trying to do so.

从API 21开始，您可以使用非常类似的命令

finishAndRemoveTask();

完成此任务中的所有活动，并将其从最近任务列表中移除。

public void quit() {
        int pid = android.os.Process.myPid();
        android.os.Process.killProcess(pid);
        System.exit(0);
    }