blocks|key|236500|text|public+enum+Gender+{
++++MALE,
++++FEMALE
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|236501|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>public enum Gender {
 MALE,
 FEMALE
}
</code></pre>

blocks|key|236516|text|你到底是在哪里找到这个语法的？Java枚举非常简单，您只需指定值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|236517|public+enum+Gender+{
+++MALE,
+++FEMALE
}|code-block|syntax|javascript|236518|如果你想让它们变得更复杂，你可以像这样给它们添加值。|236519|public+enum+Gender+{
++++MALE("Male",+0),
++++FEMALE("Female",+1);

++++private+String+stringValue;
++++private+int+intValue;
++++private+Gender(String+toString,+int+value)+{
++++++++stringValue+=+toString;
++++++++intValue+=+value;
++++}

++++@Override
++++public+String+toString()+{
++++++++return+stringValue;
++++}
}|236520|然后，要使用枚举，您可以执行如下操作：|236521|Gender+me+=+Gender.MALE|236522|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Where on earth did you find this syntax? Java Enums are very simple, you just specify the values.

<pre><code>public enum Gender {
 MALE,
 FEMALE
}
</code></pre>

If you want them to be more complex, you can add values to them like this.

<pre><code>public enum Gender {
 MALE("Male", 0),
 FEMALE("Female", 1);

 private String stringValue;
 private int intValue;
 private Gender(String toString, int value) {
 stringValue = toString;
 intValue = value;
 }

 @Override
 public String toString() {
 return stringValue;
 }
}
</code></pre>

Then to use the enum, you would do something like this:

<pre><code>Gender me = Gender.MALE
</code></pre>

blocks|key|2906768|text|围绕这一点存在一些争论，但即使在最新的文档中，android也认为在android应用程序中使用枚举并不是一个好主意。原因是它们比静态常量变量占用更多的内存。这是2014年的一篇文档，建议不要在android应用程序中使用枚举。http://developer.android.com/training/articles/memory.html#Overhead|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2906769|我引述如下：|2906770|2906771|+注意内存开销|blockquote|style|BOLD|2906772|2906773|了解你正在使用的语言和库的成本和开销，并在设计应用程序时从头到尾记住这些信息。通常，表面上看起来无害的东西实际上可能有大量的开销。示例包括：|2906774|2906775|2906776|Enums通常需要的内存是静态常量的两倍多。你应该严格避免在Android.|unordered-list-item|2906777|Every类上使用枚举(包括匿名内部类)使用大约500字节的代码。|2906778|每个类实例有12-16字节的内存开销。|2906779|将单个条目放入HashMap中需要分配一个占用32字节的附加条目对象(请参见上一节中关于优化的data+see的内容|2906780|2906781|这里或那里的几个字节很快就会累积起来--类或对象繁重的应用程序设计将受到这种开销的影响。这可能会让您在查看堆分析时陷入困境，并意识到您的问题是许多小对象占用了您的RAM。|2906782|有一些地方他们说这些建议已经过时了，不再有价值，但他们不断重复的原因，一定是有一定的道理。编写android应用程序应该尽可能保持轻量级，以获得流畅的用户体验。每一寸性能都很重要！|2906783|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/training/articles/memory.html#Overhead^0|36|1V|0|0|0|0|1|6|0|0|0|0|0|0|12|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1C|8|@]|9|@$A|1D|B|1E|1|1F]]|C|$]]|$1|D|3|E|5|6|7|1G|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|1H|8|@]|9|@]|C|$]]|$1|G|3|H|5|I|7|1I|8|@$A|1J|B|1K|J|K]]|9|@]|C|$]]|$1|L|3|-4|5|6|7|1L|8|@]|9|@]|C|$]]|$1|M|3|N|5|6|7|1M|8|@]|9|@]|C|$]]|$1|O|3|-4|5|6|7|1N|8|@]|9|@]|C|$]]|$1|P|3|-4|5|6|7|1O|8|@]|9|@]|C|$]]|$1|Q|3|R|5|S|7|1P|8|@$A|1Q|B|1R|J|K]]|9|@]|C|$]]|$1|T|3|U|5|S|7|1S|8|@]|9|@]|C|$]]|$1|V|3|W|5|S|7|1T|8|@]|9|@]|C|$]]|$1|X|3|Y|5|S|7|1U|8|@]|9|@]|C|$]]|$1|Z|3|-4|5|6|7|1V|8|@]|9|@]|C|$]]|$1|10|3|11|5|6|7|1W|8|@]|9|@]|C|$]]|$1|12|3|13|5|6|7|1X|8|@]|9|@]|C|$]]|$1|14|3|-4|5|6|7|1Y|8|@]|9|@]|C|$]]]|15|$16|$5|17|18|19|C|$1A|1B]]]]

There has been some debate around this point of contention, but even in the most recent documents android suggests that it's not such a good idea to use enums in an android application. The reason why is because they use up more memory than a static constants variable. Here is a document from a page of 2014 that advises against the use of enums in an android application. <a href="http://developer.android.com/training/articles/memory.html#Overhead">http://developer.android.com/training/articles/memory.html#Overhead</a>

I quote:

<blockquote>
 Be aware of memory overhead
 
 Be knowledgeable about the cost and overhead of the language and
 libraries you are using, and keep this information in mind when you
 design your app, from start to finish. Often, things on the surface
 that look innocuous may in fact have a large amount of overhead.
 Examples include:
 
 <ul>
 <li>Enums often require more than twice as much memory as static
 constants. You should strictly avoid using enums on Android.</li>
 <li>Every class in Java (including anonymous inner classes) uses about 500 bytes of code.</li>
 <li>Every class instance has 12-16 bytes of RAM overhead. </li>
 <li>Putting a single entry into a HashMap requires the allocation of an
 additional
 entry object that takes 32 bytes (see the previous section about
 optimized data containers).</li>
 </ul>
 
 A few bytes here and there quickly add
 up—app designs that are class- or object-heavy will suffer from this
 overhead. That can leave you in the difficult position of looking at a
 heap analysis and realizing your problem is a lot of small objects
 using up your RAM.
</blockquote>

There has been some places where they say that these tips are outdated and no longer valuable, but the reason they keep repeating it, must be there is some truth to it. Writing an android application is something you should keep as lightweight as possible for a smooth user experience. And every little inch of performance counts!

blocks|key|238927|text|正如Chris评论的那样，枚举在Android上需要更多的内存，随着它们在任何地方的使用，这些内存都会增加。您应该尝试使用IntDef或StringDef，它们使用注释，以便编译器验证传递的值。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|238928|public+abstract+class+ActionBar+{
...
@IntDef({NAVIGATION_MODE_STANDARD,+NAVIGATION_MODE_LIST,+NAVIGATION_MODE_TABS})
@Retention(RetentionPolicy.SOURCE)
public+@interface+NavigationMode+{}

public+static+final+int+NAVIGATION_MODE_STANDARD+=+0;
public+static+final+int+NAVIGATION_MODE_LIST+=+1;
public+static+final+int+NAVIGATION_MODE_TABS+=+2;

@NavigationMode
public+abstract+int+getNavigationMode();

public+abstract+void+setNavigationMode(@NavigationMode+int+mode);|code-block|syntax|javascript|238929|它还可以用作标志，允许二进制组合(OR+/+AND操作)。|238930|编辑：似乎将枚举转换为It是one+of+the+default+optimizations+in+Proguard。|style|BOLD|238931|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.android.com/reference/android/support/annotation/IntDef.html|1|https://developer.android.com/reference/android/support/annotation/StringDef.html|2|https://stackoverflow.com/questions/32236870/does-proguard-converts-all-enums-to-int-or-needs-to-be-configured-for-this^0|1P|6|0|1W|9|1|0|0|0|0|2|E|18|2|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]|$A|14|B|15|1|16]]|C|$]]|$1|D|3|E|5|F|7|17|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|18|8|@]|9|@]|C|$]]|$1|K|3|L|5|6|7|19|8|@$A|1A|B|1B|M|N]]|9|@$A|1C|B|1D|1|1E]]|C|$]]|$1|O|3|-4|5|6|7|1F|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]|W|$5|R|S|T|C|$U|X]]|Y|$5|R|S|T|C|$U|Z]]]]

As commented by Chris, enums require much more memory on Android that adds up as they keep being used everywhere. You should try <a href="https://developer.android.com/reference/android/support/annotation/IntDef.html" rel="noreferrer">IntDef</a> or <a href="https://developer.android.com/reference/android/support/annotation/StringDef.html" rel="noreferrer">StringDef</a> instead, which use annotations so that the compiler validates passed values.

<pre><code>public abstract class ActionBar {
...
@IntDef({NAVIGATION_MODE_STANDARD, NAVIGATION_MODE_LIST, NAVIGATION_MODE_TABS})
@Retention(RetentionPolicy.SOURCE)
public @interface NavigationMode {}

public static final int NAVIGATION_MODE_STANDARD = 0;
public static final int NAVIGATION_MODE_LIST = 1;
public static final int NAVIGATION_MODE_TABS = 2;

@NavigationMode
public abstract int getNavigationMode();

public abstract void setNavigationMode(@NavigationMode int mode);
</code></pre>

It can also be used as flags, allowing for binary composition (OR / AND operations).

EDIT: It seems that transforming enums into ints is <a href="https://stackoverflow.com/questions/32236870/does-proguard-converts-all-enums-to-int-or-needs-to-be-configured-for-this">one of the default optimizations in Proguard</a>.

blocks|key|3121077|text|根据这个Video，如果您使用ProGuard，您甚至不需要考虑枚举性能问题！！|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3121078|在许多情况下，|3121079|+Proguard可以代表您将枚举优化为int值，因此真的不需要考虑它或做任何工作。|blockquote|3121080|3121081|entityMap|0|LINK|mutability|MUTABLE|url|https://www.youtube.com/watch?v=Hzs6OBcvNQE^0|4|5|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|W|8|@]|9|@]|C|$]]|$1|I|3|-4|5|6|7|X|8|@]|9|@]|C|$]]|$1|J|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|K|$L|$5|M|N|O|C|$P|Q]]]]

According to this <a href="https://www.youtube.com/watch?v=Hzs6OBcvNQE" rel="noreferrer">Video</a> if you use the ProGuard you don't need even think about Enums performance issues!!

<blockquote>
 Proguard can in many situations optimize Enums to INT values on your behalf so really don't need to think about it or do any work.
</blockquote>

blocks|key|2906854|text|Android的首选方法是使用@IntDef强制使用int常量：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2906855|public+static+final+int+GENDER_MALE+=+1;
public+static+final+int+GENDER_FEMALE+=+2;

@Retention(RetentionPolicy.SOURCE)
@IntDef+({GENDER_MALE,+GENDER_FEMALE})
public+@interface+Gender{}

//+Example+usage...
void+exampleFunc(@Gender+int+gender)+{
++switch(gender)+{
++case+GENDER_MALE:

+++++break;
++case+GENDER_FEMALE:
+++++//+TODO
+++++break;
++}
}|code-block|syntax|javascript|2906856|文档：https://developer.android.com/studio/write/annotations.html#enum-annotations|offset|length|2906857|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.android.com/studio/write/annotations.html#enum-annotations^0|0|0|3|24|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Android's preferred approach is int constants enforced with @IntDef:

<pre><code>public static final int GENDER_MALE = 1;
public static final int GENDER_FEMALE = 2;

@Retention(RetentionPolicy.SOURCE)
@IntDef ({GENDER_MALE, GENDER_FEMALE})
public @interface Gender{}

// Example usage...
void exampleFunc(@Gender int gender) {
 switch(gender) {
 case GENDER_MALE:

 break;
 case GENDER_FEMALE:
 // TODO
 break;
 }
}
</code></pre>

Docs: <a href="https://developer.android.com/studio/write/annotations.html#enum-annotations" rel="noreferrer">https://developer.android.com/studio/write/annotations.html#enum-annotations</a>

I am almost done with a calculation activity I am working with in android for my app. I try to create a Gender Enum, but for some reason getting Syntax error, insert "EnumBody" to complete EnumDeclaration.

<pre><code>public static enum Gender
{
 static
 {
 Female = new Gender("Female", 1);
 Gender[] arrayOfGender = new Gender[2];
 arrayOfGender[0] = Male;
 arrayOfGender[1] = Female;
 ENUM$VALUES = arrayOfGender;
 }
}
</code></pre>

I have also tried it without the static {} but I get the same syntax error.

Working with Enums in android

编译器

Android

Java

我几乎完成了我在android中为我的应用程序处理的一个计算活动。我尝试创建一个性别枚举，但由于某种原因得到语法错误，插入"EnumBody“以完成EnumDeclaration。public static enum Gender{    static    {        Female = new Gender("...

问在android中使用枚举
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