blocks|key|1001538|text|通过相同的代码，它会在非活动的上下文中使用LayoutInflater.from。我假设使用活动的充气器会重用已经创建的充气器，而另一种选择则会从上下文中创建一个布局充气器。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1001539|我要做的唯一更改是将上下文保存在变量中，以防止重复调用相同的函数并从对象中检索相同的值：|1001540|Context+ctx+=+getContext();
if(ctx+instanceof+Activity)+{
++inflater+=+((Activity)ctx).getLayoutInflater();
}
else+{
++inflater+=+LayoutInflater.from(ctx);
}|code-block|syntax|javascript|1001541|Android有很多优化，可以在可用时重用项目，比如可以重用的ListViews视图。|1001542|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

By the same code it seams that LayoutInflater.from is used in the contexts that are not an activity. I would assume that using the Activity's inflater reuses an already created inflater versus the other choice which would create a layoutinflater from a context.

The only change I would make is saving the context in a variable to prevent calling the same function and retrieving the same value from the object repeatedly:

<pre><code>Context ctx = getContext();
if(ctx instanceof Activity) {
 inflater = ((Activity)ctx).getLayoutInflater();
}
else {
 inflater = LayoutInflater.from(ctx);
}
</code></pre>

Android has a lot of optimizations in place to reuse items when available, like the views for ListViews which can be reused.

blocks|key|1722243|text|其实没什么大不了的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1722244|活性Window.Window+PhoneWindow的通常策略实现依次是LayoutInflater.from(context)，其中context是活动。|offset|length|style|CODE|1722245|因此，充气器对象实际上是相同的，在活动的情况下使用相同的Context。|1722246|LayoutInflater.from()真的是Context.getSystemService()。现在，系统服务是looked+up+by+name+from+a+map，然后是retrieved+from+a+cache。与访问Activity中已经初始化的成员变量相比，此查找具有一定的开销。|1722247|因此，与实际视图层次结构膨胀相比，这似乎是一种微优化，不会对运行时性能产生多大影响。|1722248|这种优化实际上会对开发人员的生产力产生负面影响，因为人们需要停下来思考代码存在的原因。|1722249|entityMap|0|LINK|mutability|MUTABLE|url|http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/app/Activity.java#3337|1|http://androidxref.com/4.4.4_r1/xref/frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindow.java#239|2|http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/view/LayoutInflater.java#210|3|http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/app/ContextImpl.java#1630|4|http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/app/ContextImpl.java#242^0|0|2|6|9|6|G|B|11|S|1W|7|2|6|0|11|S|1|0|S|7|0|0|L|O|Q|39|8|O|Q|2|1N|S|3|2J|M|4|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@$D|17|E|18|F|G]|$D|19|E|1A|F|G]|$D|1B|E|1C|F|G]|$D|1D|E|1E|F|G]|$D|1F|E|1G|F|G]]|9|@$D|1H|E|1I|1|1J]|$D|1K|E|1L|1|1M]]|A|$]]|$1|H|3|I|5|6|7|1N|8|@$D|1O|E|1P|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|1Q|8|@$D|1R|E|1S|F|G]|$D|1T|E|1U|F|G]|$D|1V|E|1W|F|G]]|9|@$D|1X|E|1Y|1|1Z]|$D|20|E|21|1|22]|$D|23|E|24|1|25]]|A|$]]|$1|L|3|M|5|6|7|26|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|27|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|28|8|@]|9|@]|A|$]]]|Q|$R|$5|S|T|U|A|$V|W]]|X|$5|S|T|U|A|$V|Y]]|Z|$5|S|T|U|A|$V|10]]|11|$5|S|T|U|A|$V|12]]|13|$5|S|T|U|A|$V|14]]]]

It doesn't really matter much.

Activity <a href="http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/app/Activity.java#3337">delegates <code>getLayouInflater()</code> to <code>Window</code></a>. The usual policy implementation of <code>Window</code> <code>PhoneWindow</code> in turn <a href="http://androidxref.com/4.4.4_r1/xref/frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindow.java#239">initializes its inflater with <code>LayoutInflater.from(context)</code></a> where <code>context</code> is the activity.

So the inflater object is really the same, using the same <code>Context</code> in case of an activity.

<code>LayoutInflater.from()</code> is really a <a href="http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/view/LayoutInflater.java#210">wrapper for <code>Context.getSystemService()</code></a>. Now, system services are <a href="http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/app/ContextImpl.java#1630">looked up by name from a map</a> and then <a href="http://androidxref.com/4.4.4_r1/xref/frameworks/base/core/java/android/app/ContextImpl.java#242">retrieved from a cache</a>. This lookup has some overhead when compared to accessing an already initialized member variable in <code>Activity</code>.

So it smells like a micro optimization that does not likely affect much runtime performance when compared to actual view hierarchy inflation.

This optimization can actually have negative impact on developer productivity as people need to stop and spend some thinking why the code is there.

blocks|key|1296538|text|从android文档来看，建议使用getLayoutInflater(+)+instead.The文档来描述LayoutInflator.from。：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1296539|将布局XML文件实例化到其相应的View对象中。它从来没有直接使用过。相反，
|blockquote|1296540|1296541|它建议使用：|1296542|使用Activity.getLayoutInflater()或Context#getSystemService检索已经连接到当前上下文并为正在运行的设备正确配置的标准LayoutInflater实例。
|1296543|1296544|换句话说，为了更简单的代码和性能，您最好从已经初始化的上下文中使用getLayoutInflater。|1296545|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$]]|$1|E|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|D|7|S|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

from the android documentation it is suggested to use getLayoutInflater( ) instead.The documentation says the following about the LayoutInflator.from.. :
<blockquote>
Instantiates a layout XML file into its corresponding View objects. It
is never used directly. Instead,
</blockquote>
it suggests to use :
<blockquote>
use Activity.getLayoutInflater() or
Context#getSystemService to retrieve a standard LayoutInflater
instance that is already hooked up to the current context and
correctly configured for the device you are running on.
</blockquote>
in other words for the sake of simpler code and performance you better use getLayoutInflater from the context that has already been initilized.

Studying some (known to be good) code I can see the logic as follows:

<pre><code>if (getContext() instanceof Activity) {
 inflater=((Activity)getContext()).getLayoutInflater();
}
 else {
 inflater=LayoutInflater.from(getContext());
}
</code></pre>

I wonder, why this <code>if/else</code>, how it is better to, just, using <code>LayoutInflater.from</code> in all cases?

getLayoutInflater vs LayoutInflater.from

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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学习一些(已知是好的)代码，我可以看到如下的逻辑：if (getContext() instanceof Activity) {      inflater=((Activity)getContext()).getLayoutInflater();}    else {      inflater=LayoutInfl...

问getLayoutInflater对LayoutInflater.from
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