blocks|key|968197|text|只要您的设备不停止活动(例如，由于系统资源不足)，那么每当您离开应用程序并返回时，都会调用onStart。但是，如果应用程序进程被终止，那么当您返回时，将再次调用onCreate，因为您的所有资源都将被释放。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|968198|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

As long as your device does not kill the activity, for example due to low system resources, then any time you leave your app and go back, onStart is called. If however the application process is killed, then when you return onCreate will be called again, because all of your resources will have been released.

blocks|key|968254|text|这些文档--我不是开玩笑--有一个非常非常漂亮的形象来描述Activity生命周期(它是如何开始、工作和完成的)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|968255|直接链接到这里的图像基本上是这样写的：|968256|onCreate()在创建Activity时被调用；也就是说，它是启动或启动的。(此外，这将在更改方向时触发。)进程终止时再次调用它，然后返回到。|unordered-list-item|968257|在启动时，onStart()在onCreate()之后被调用。此外，当应用程序被导航回onStop()后(以及跟随onRestart())时，它也会被调用，这是在Activity不再可见之后发生的(这是在“用户可以在屏幕上看到活动，尽管它可能不在前台并与用户交互的时间”)。|968258|这张图表诚实地用不到1000个字解释得比我好。|968259|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle|1|http://developer.android.com/images/activity_lifecycle.png^0|T|8|H|9|0|0|5|2|1|0|0|A|D|8|0|5|9|F|A|17|8|1L|B|29|8|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|6|7|14|8|@]|D|@$9|15|A|16|1|17]]|E|$]]|$1|H|3|I|5|J|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|K|3|L|5|J|7|1D|8|@$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]|$9|1M|A|1N|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|1O|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1P|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]]]

The documentation seriously--I'm not kidding--has a <a href="http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle" rel="noreferrer">very, very pretty image</a> that describes how the <code>Activity</code> lifecycle (how it starts, works, and finishes) operates.

The image, directly linked <a href="http://developer.android.com/images/activity_lifecycle.png" rel="noreferrer">here</a>, basically says this:

<ul>
<li><code>onCreate()</code> is called when the <code>Activity</code> is created; that is, it is launched or started. (Additionally, this triggers when the orientation is changed.) It is called again when the process is killed, then returned to.</li>
<li><code>onStart()</code> is called following <code>onCreate()</code> at startup. Additionally, it is also called when the app is navigated back to after <code>onStop()</code> (and following <code>onRestart()</code>), which occurs after the <code>Activity</code> is no longer visible (which is during the time that "the user can see the activity on-screen, though it may not be in the foreground and interacting with the user").</li>
</ul>

The diagram honestly explains it better than I can in less than 1,000 words.

blocks|key|966562|text|最好的解释是从相反的函数开始:+onDestroy和onStop。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|966563|当活动被释放或关闭时，将调用onDestroy。下一次打开它时，将调用onCreate。|966564|每当应用程序脱离视图并不再可见时，都会调用onStop。这通常是由在旧活动的顶部创建的新活动造成的。当活动再次可见时，将调用onStart。|966565|这个页面上的图表非常好地解释了活动可以进入的各种状态，以及相关的转换方法：http://developer.android.com/training/basics/activity-lifecycle/starting.html。|offset|length|966566|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/training/basics/activity-lifecycle/starting.html^0|0|0|0|11|25|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|U|8|@]|9|@$H|V|I|W|1|X]]|A|$]]|$1|J|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q]]]]

This is perhaps best explained by starting with the opposite functions: onDestroy and onStop.

onDestroy is called when an activity is disposed of or shut down. The next time it's opened, onCreate is called.

onStop is called whenever an application goes out of view, and is no longer visible. This is usually caused by a new activity being created over the top of the old one. When the activity becomes visible again, onStart is called.

The diagram on this page does a really good job of explaining the various states an activity can be in, along with the relevant transition methods: <a href="http://developer.android.com/training/basics/activity-lifecycle/starting.html" rel="nofollow">http://developer.android.com/training/basics/activity-lifecycle/starting.html</a>

blocks|key|1949525|text|差不多了。onCreate通常在应用程序启动时被调用，但如果活动由于其他原因被破坏/发布，也可能被调用。基本上，如果您想为该活动做一次设置，则应该重写onCreate。如果您想在每次用户导航到该活动时执行某些操作，则应该重写onStart。如果您想在每次活动变为可见/活动时执行某些操作，请使用onResume。如果你想为整个应用程序做一次设置，即只运行一次，你应该使用onCreate，但是检查一下你是否做过这个设置，只有当你没有这样做的时候。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1949526|查看这个页面上非常有用的图表：活动参考|offset|length|1949527|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/reference/android/app/Activity.html^0|0|F|4|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

Almost. onCreate is usually called when the app starts, but may also be called if the Activity is destroyed/released for other reasons. Basically, if you want to do one time set-up for the Activity, you should override onCreate. If you want to do something each time the user navigates to the Activity you should override onStart. If you want to do something each time the Activity becomes visible/active, use onResume. If you want to do one-time set up for the whole app, i.e. only runs once EVER, you should use onCreate, but check to see if you've done that set up, and only do it if you have not.

Check out the very useful diagram on this page: <a href="http://developer.android.com/reference/android/app/Activity.html" rel="nofollow">Activity reference</a>

blocks|key|1949462|text|这个网站为Android生命周期提供了一个坚实的图形表示：http://developer.android.com/training/basics/activity-lifecycle/starting.html。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1949463|每当应用程序可见时，都会调用onStart()。这包括应用程序第一次创建的时间以及在不被终止的情况下将其带回屏幕的时间。第二种行为发生在用户切换应用程序而应用程序处于后台时。当应用程序变得不可见时，将调用onStop()，但当应用程序完全“销毁”时，则调用onDestroy()。在onDestroy()调用之后，必须在生命周期开始时再次创建应用程序。|style|CODE|1949464|需要注意的是，在应用程序由于对话框之类的原因而失去焦点之后，不会调用onStart()。在这种情况下，当焦点重获时，onPause()被称为onResume()，然后是onResume()。|1949465|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/training/basics/activity-lifecycle/starting.html^0|T|25|0|0|E|9|2U|8|3K|B|3X|B|0|Y|9|1M|9|1Y|A|2C|A|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@$A|W|B|X|F|G]|$A|Y|B|Z|F|G]|$A|10|B|11|F|G]|$A|12|B|13|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|14|8|@$A|15|B|16|F|G]|$A|17|B|18|F|G]|$A|19|B|1A|F|G]|$A|1B|B|1C|F|G]]|9|@]|C|$]]|$1|J|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]]]

This website provides a solid graphical representation of the Android lifecycle: <a href="http://developer.android.com/training/basics/activity-lifecycle/starting.html" rel="nofollow">http://developer.android.com/training/basics/activity-lifecycle/starting.html</a>

<code>onStart()</code> is called whenever the application becomes visible. This includes when the application is first created and when it is brought back on the screen without being terminated. This second behavior occurs when a user switches applications and the app is sitting in the background. When the application becomes invisible, <code>onStop()</code> is called, but when the application is completely "destroyed", <code>onDestroy()</code> is called. After an <code>onDestroy()</code> call, the application must be created again at the beginning of the lifecycle.

It is important to note that <code>onStart()</code> is not called after the application simply loses focus due to something like a dialog. In such situations, <code>onPause()</code> is called followed by <code>onResume()</code> when focus is regained

<blockquote>
 Possible Duplicate: 
 <a href="https://stackoverflow.com/questions/6812003/difference-between-oncreate-and-onstart">Difference between onCreate() and onStart()?</a> 
 <a href="https://stackoverflow.com/questions/8515936/android-activity-life-cycle-what-are-all-these-methods-for">Android Activity Life Cycle - What are all these methods for?</a> 
</blockquote>



What is the difference between OnCreate and OnStart?

My understanding is that OnCreate is only called the very first time the application is opened and is never called again. Is this true? Can someone please elaborate in their own words rather than copying and pasting a definition? Thank you!

OnCreate() vs OnStart()

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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可能重复：OnCreate和OnStart有什么区别？我的理解是，OnCreate只是在应用程序第一次打开时才被调用，再也不会被调用。这是真的吗？有人能不能用他们自己的话详细说明一下，而不是抄袭和粘贴一个定义呢？谢谢!

问OnCreate()与OnStart()
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