blocks|key|1009978|text|改用Apache+commons+lang3库。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009979|+EnumUtils.isValidEnum(MyEnum.class,+myValue)|code-block|syntax|javascript|1009980|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use the Apache commons lang3 lib instead

<pre><code> EnumUtils.isValidEnum(MyEnum.class, myValue)
</code></pre>

blocks|key|1010137|text|如果你使用的是Java+1.8，你可以选择Stream+%2B+Lambda来实现：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010138|public+enum+Period+{
++++DAILY,+WEEKLY
};

//This+is+recommended
Arrays.stream(Period.values()).anyMatch((t)+->+t.name().equals("DAILY1"));
//May+throw+java.lang.IllegalArgumentException
Arrays.stream(Period.values()).anyMatch(Period.valueOf("DAILY")::equals);|code-block|syntax|javascript|1010139|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are using Java 1.8, you can choose Stream + Lambda to implement this:

<pre><code>public enum Period {
 DAILY, WEEKLY
};

//This is recommended
Arrays.stream(Period.values()).anyMatch((t) -&gt; t.name().equals("DAILY1"));
//May throw java.lang.IllegalArgumentException
Arrays.stream(Period.values()).anyMatch(Period.valueOf("DAILY")::equals);
</code></pre>

blocks|key|795549|text|Guavas+Enums可以成为你的朋友|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|795550|就像这样：|795551|enum+MyData+{
++++ONE,
++++TWO
}

@Test
public+void+test()+{

++++if+(!Enums.getIfPresent(MyData.class,+"THREE").isPresent())+{
++++++++System.out.println("THREE+is+not+here");
++++}
}|code-block|syntax|javascript|795552|entityMap|0|LINK|mutability|MUTABLE|url|https://guava.dev/releases/19.0/api/docs/index.html?com/google/common/base/Enums.html^0|0|C|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

<h2><a href="https://guava.dev/releases/19.0/api/docs/index.html?com/google/common/base/Enums.html" rel="nofollow noreferrer">Guavas Enums</a> could be your friend</h2>

Like e.g. this:

<pre><code>enum MyData {
 ONE,
 TWO
}

@Test
public void test() {

 if (!Enums.getIfPresent(MyData.class, "THREE").isPresent()) {
 System.out.println("THREE is not here");
 }
}
</code></pre>

blocks|key|795336|text|更好的是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|795337|enum+choices+{
+++a1,+a2,+b1,+b2;

++public+static+boolean+contains(String+s)
++{
++++++for(choices+choice:values())
+++++++++++if+(choice.name().equals(s))+
++++++++++++++return+true;
++++++return+false;
++}+

};|code-block|syntax|javascript|795338|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Even better:

<pre><code>enum choices {
 a1, a2, b1, b2;

 public static boolean contains(String s)
 {
 for(choices choice:values())
 if (choice.name().equals(s)) 
 return true;
 return false;
 } 

};
</code></pre>

blocks|key|1010158|text|您可以先将枚举转换为List，然后使用list+contains方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010159|enum+Choices{A1,+A2,+B1,+B2};

List+choices+=+Arrays.asList(Choices.values());

//compare+with+enum+value+
if(choices.contains(Choices.A1)){
+++//do+something
}

//compare+with+String+value
if(choices.contains(Choices.valueOf("A1"))){
+++//do+something
}|code-block|syntax|javascript|1010160|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can first convert the enum to List and then use list contains method

<pre><code>enum Choices{A1, A2, B1, B2};

List choices = Arrays.asList(Choices.values());

//compare with enum value 
if(choices.contains(Choices.A1)){
 //do something
}

//compare with String value
if(choices.contains(Choices.valueOf("A1"))){
 //do something
}
</code></pre>

blocks|key|796130|text|这里提到了几个库，但我错过了我真正想要的库:+Spring！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|796131|默认情况下，ObjectUtils#containsConstant是不区分大小写的，但如果您愿意，也可以是严格的。它的用法如下：|offset|length|796132|if(ObjectUtils.containsConstant(Choices.values(),+"SOME_CHOISE",+true)){
//+do+stuff
}|code-block|syntax|javascript|796133|注意:我在这里使用了重载方法来演示如何使用区分大小写的检查。您可以省略布尔值以获得不区分大小写的行为。|796134|不过，要小心大型枚举，因为它们不像某些枚举那样使用Map实现……|796135|另外，它还提供了valueOf的不区分大小写的变体：ObjectUtils#caseInsensitiveValueOf|796136|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/util/ObjectUtils.html#containsConstant-java.lang.Enum:A-java.lang.String-|1|https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/util/ObjectUtils.html#caseInsensitiveValueOf-E:A-java.lang.String-^0|0|6|S|0|0|0|0|0|Q|Y|1|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@$D|12|E|13|1|14]]|A|$]]|$1|F|3|G|5|H|7|15|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|16|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|18|8|@]|9|@$D|19|E|1A|1|1B]]|A|$]]|$1|Q|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]|Y|$5|T|U|V|A|$W|Z]]]]

A couple libraries have been mentioned here, but I miss the one that I was actually looking for: Spring!

There is the <a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/util/ObjectUtils.html#containsConstant-java.lang.Enum:A-java.lang.String-" rel="noreferrer">ObjectUtils#containsConstant</a> which is case insensitive by default, but can be strict if you want. It is used like this:

<pre class="lang-java prettyprint-override"><code>if(ObjectUtils.containsConstant(Choices.values(), "SOME_CHOISE", true)){
// do stuff
}
</code></pre>

Note: I used the overloaded method here to demonstrate how to use case sensitive check. You can omit the boolean to have case insensitive behaviour.

Be careful with large enums though, as they don't use the Map implementation as some do...

As a bonus, it also provides a case insensitive variant of the valueOf: <a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/util/ObjectUtils.html#caseInsensitiveValueOf-E:A-java.lang.String-" rel="noreferrer">ObjectUtils#caseInsensitiveValueOf</a>

blocks|key|1010108|text|以下是一些假设：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010109|1)无try/catch，异常流控|1010110|2)“包含”方法必须是快速的，因为它通常会运行几次。|1010111|3)空间不受限制(普通解决方案常见)|1010112|import+java.util.HashSet;
import+java.util.Set;

enum+Choices+{
++++a1,+a2,+b1,+b2;

++++private+static+Set<String>+_values+=+new+HashSet<>();

++++//+O(n)+-+runs+once
++++static{
++++++++for+(Choices+choice+:+Choices.values())+{
++++++++++++_values.add(choice.name());
++++++++}
++++}

++++//+O(1)+-+runs+several+times
++++public+static+boolean+contains(String+value){
++++++++return+_values.contains(value);
++++}
}|code-block|syntax|javascript|1010113|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|S|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Few assumptions: 
1) No try/catch, as it is exceptional flow control 
2) 'contains' method has to be quick, as it usually runs several times. 
3) Space is not limited (common for ordinary solutions) 

<pre><code>import java.util.HashSet;
import java.util.Set;

enum Choices {
 a1, a2, b1, b2;

 private static Set&lt;String&gt; _values = new HashSet&lt;&gt;();

 // O(n) - runs once
 static{
 for (Choices choice : Choices.values()) {
 _values.add(choice.name());
 }
 }

 // O(1) - runs several times
 public static boolean contains(String value){
 return _values.contains(value);
 }
}
</code></pre>

blocks|key|795505|text|你可以使用这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|795506|YourEnum+{A1，A2，B1，B2}|795507|boolean+contains(String+str){+
++++return+Sets.newHashSet(YourEnum.values()).contains(str);
}++++++++++++++++++++++++++++++++++|code-block|syntax|javascript|795508|由@wightwulf1944建议的更新被纳入以使解决方案更有效。|795509|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|$]]

You can use this

YourEnum {A1, A2, B1, B2}

<pre><code>boolean contains(String str){ 
 return Sets.newHashSet(YourEnum.values()).contains(str);
} 
</code></pre>

Update suggested by @wightwulf1944 is incorporated to make the solution more efficient.

blocks|key|1010345|text|Java+Streams提供了一种很好的方法来实现这一点|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010346|Stream.of(MyEnum.values()).anyMatch(v+->+v.name().equals(strValue))|code-block|syntax|javascript|1010347|返回:如果流的任何元素与提供的值匹配，则返回true；否则返回false|1010348|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Java Streams provides elegant way to do that

<pre class="lang-java prettyprint-override"><code>Stream.of(MyEnum.values()).anyMatch(v -&gt; v.name().equals(strValue))
</code></pre>

Returns:
true if any elements of the stream match the provided value, otherwise false

blocks|key|1009713|text|我不认为有，但你可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009714|enum+choices+{a1,+a2,+b1,+b2};

public+static+boolean+exists(choices+choice)+{
+++for(choice+aChoice+:+choices.values())+{
++++++if(aChoice+==+choice)+{
+++++++++return+true;
++++++}
+++}
+++return+false;
}|code-block|syntax|javascript|1009715|编辑：|1009716|请参阅Richard的版本，因为它更合适，因为除非您将其转换为使用Strings，否则它不会工作，Richards就是这样做的。|1009717|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I don't think there is, but you can do something like this:

<pre><code>enum choices {a1, a2, b1, b2};

public static boolean exists(choices choice) {
 for(choice aChoice : choices.values()) {
 if(aChoice == choice) {
 return true;
 }
 }
 return false;
}
</code></pre>

Edit:

Please see Richard's version of this as it is more appropriate as this won't work unless you convert it to use Strings, which Richards does.

blocks|key|1009884|text|为什么不把Pablo的回复和valueOf()结合起来呢？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009885|public+enum+Choices
{
++++a1,+a2,+b1,+b2;

++++public+static+boolean+contains(String+s)+{
++++++++try+{
++++++++++++Choices.valueOf(s);
++++++++++++return+true;
++++++++}+catch+(Exception+e)+{
++++++++++++return+false;
++++++++}
}|code-block|syntax|javascript|1009886|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Why not combine Pablo's reply with a valueOf()?

<pre><code>public enum Choices
{
 a1, a2, b1, b2;

 public static boolean contains(String s) {
 try {
 Choices.valueOf(s);
 return true;
 } catch (Exception e) {
 return false;
 }
}
</code></pre>

blocks|key|1010840|text|我只会写，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010841|Arrays.stream(Choice.values()).map(Enum::name).collect(Collectors.toList()).contains("a1");|code-block|syntax|javascript|1010842|Enum#equals仅适用于对象比较。|1010843|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I would just write,

<pre><code>Arrays.stream(Choice.values()).map(Enum::name).collect(Collectors.toList()).contains("a1");
</code></pre>

Enum#equals only works with object compare.

blocks|key|796085|text|此方法可用于检查任何Enum，您可以将其添加到Utils类中：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|796086|public+static+<T+extends+Enum<T>>+boolean+enumContains(Class<T>+enumerator,+String+value)
{
++++for+(T+c+:+enumerator.getEnumConstants())+{
++++++++if+(c.name().equals(value))+{
++++++++++++return+true;
++++++++}
++++}
++++return+false;
}|code-block|syntax|javascript|796087|这样使用它：|796088|boolean+isContained+=+Utils.enumContains(choices.class,+"value");|796089|entityMap^0|A|4|N|5|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

This approach can be used to check any <code>Enum</code>, you can add it to an <code>Utils</code> class:

<pre><code>public static &lt;T extends Enum&lt;T&gt;&gt; boolean enumContains(Class&lt;T&gt; enumerator, String value)
{
 for (T c : enumerator.getEnumConstants()) {
 if (c.name().equals(value)) {
 return true;
 }
 }
 return false;
}
</code></pre>

Use it this way:

<pre><code>boolean isContained = Utils.enumContains(choices.class, "value");
</code></pre>

blocks|key|1010270|text|这一条对我很有效：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010271|Arrays.asList(YourEnum.values()).toString().contains("valueToCheck");|code-block|syntax|javascript|1010272|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This one works for me:

<pre><code>Arrays.asList(YourEnum.values()).toString().contains("valueToCheck");
</code></pre>

blocks|key|1010297|text|我为这个验证创建了下一个类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010298|public+class+EnumUtils+{

++++public+static+boolean+isPresent(Enum+enumArray[],+String+name)+{
++++++++for+(Enum+element:+enumArray+)+{
++++++++++++if(element.toString().equals(name))
++++++++++++++++return+true;
++++++++}
++++++++return+false;
++++}

}|code-block|syntax|javascript|1010299|用法示例：|1010300|public+ArrivalEnum+findArrivalEnum(String+name)+{

++++if+(!EnumUtils.isPresent(ArrivalEnum.values(),+name))
++++++++throw+new+EnumConstantNotPresentException(ArrivalEnum.class,"Arrival+value+must+be+'FROM_AIRPORT'+or+'TO_AIRPORT'+");

++++return+ArrivalEnum.valueOf(name);
}|1010301|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I created the next class for this validation

<pre class="lang-js prettyprint-override"><code>public class EnumUtils {

 public static boolean isPresent(Enum enumArray[], String name) {
 for (Enum element: enumArray ) {
 if(element.toString().equals(name))
 return true;
 }
 return false;
 }

}
</code></pre>

example of usage :

<pre><code>public ArrivalEnum findArrivalEnum(String name) {

 if (!EnumUtils.isPresent(ArrivalEnum.values(), name))
 throw new EnumConstantNotPresentException(ArrivalEnum.class,"Arrival value must be 'FROM_AIRPORT' or 'TO_AIRPORT' ");

 return ArrivalEnum.valueOf(name);
}
</code></pre>

blocks|key|1010318|text|如果您使用的是Java+8或更高版本，则可以执行以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010319|boolean+isPresent(String+testString){
++++++return+Stream.of(Choices.values()).map(Enum::name).collect(Collectors.toSet()).contains(testString);
}|code-block|syntax|javascript|1010320|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are Using Java 8 or above, you can do this : 

<pre><code>boolean isPresent(String testString){
 return Stream.of(Choices.values()).map(Enum::name).collect(Collectors.toSet()).contains(testString);
}
</code></pre>

blocks|key|1010374|text|您可以将其作为包含方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010375|enum+choices+{a1,+a2,+b1,+b2};
public+boolean+contains(String+value){
++++try{
++++++++EnumSet.allOf(choices.class).contains(Enum.valueOf(choices.class,+value));
++++++++return+true;
++++}catch+(Exception+e)+{
++++++++return+false;
++++}
}|code-block|syntax|javascript|1010376|或者你可以直接在你的代码块中使用它：|1010377|try{
++++EnumSet.allOf(choices.class).contains(Enum.valueOf(choices.class,+"a1"));
++++//do+something
}catch+(Exception+e)+{
++++//do+something+else
}|1010378|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can make it as a contains method:

<pre><code>enum choices {a1, a2, b1, b2};
public boolean contains(String value){
 try{
 EnumSet.allOf(choices.class).contains(Enum.valueOf(choices.class, value));
 return true;
 }catch (Exception e) {
 return false;
 }
}

</code></pre>

or you can just use it with your code block:

<pre><code>try{
 EnumSet.allOf(choices.class).contains(Enum.valueOf(choices.class, "a1"));
 //do something
}catch (Exception e) {
 //do something else
}

</code></pre>

blocks|key|795237|text|如果要按字符串查找，可以使用valueOf("a1")|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|795238|entityMap^0|E|D|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

You can use <code>valueOf("a1")</code> if you want to look up by String

blocks|key|1009838|text|它是一个枚举，那些是常量值，所以如果它在switch语句中，它只是这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009839|case:+val1
case:+val2|code-block|syntax|javascript|1009840|还有，为什么你需要知道什么被声明为常量呢？|1009841|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

It is an enum, those are constant values so if its in a switch statement its just doing something like this:

<pre><code>case: val1
case: val2
</code></pre>

Also why would you need to know what is declared as a constant?

blocks|key|795408|text|使用芭乐就更简单了：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|795409|boolean+isPartOfMyEnum(String+myString){

return+Lists.newArrayList(MyEnum.values().toString()).contains(myString);

}|code-block|syntax|javascript|795410|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

With guava it's even simpler:

<pre><code>boolean isPartOfMyEnum(String myString){

return Lists.newArrayList(MyEnum.values().toString()).contains(myString);

}
</code></pre>

blocks|key|1009956|text|这结合了前面方法中的所有方法，并且应该具有相同的性能。它可以用于任何枚举，内联@Richard+H中的"Edit“解决方案，并对@bestsss等无效值使用异常。唯一的权衡是需要指定类，但这会使其成为双行代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1009957|import+java.util.EnumSet;

public+class+HelloWorld+{

static+enum+Choices+{a1,+a2,+b1,+b2}

public+static+<E+extends+Enum<E>>+boolean+contains(Class<E>+_enumClass,+String+value)+{
++++try+{
++++++++return+EnumSet.allOf(_enumClass).contains(Enum.valueOf(_enumClass,+value));++++
++++}+catch+(Exception+e)+{
++++++++return+false;+
++++}
}

public+static+void+main(String[]+args)+{
++++for+(String+value+:+new+String[]+{"a1",+"a3",+null})+{
++++++++System.out.println(contains(Choices.class,+value));
++++}
}|code-block|syntax|javascript|1009958|}|1009959|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This combines all of the approaches from previous methods and should have equivalent performance. It can be used for any enum, inlines the "Edit" solution from @Richard H, and uses Exceptions for invalid values like @bestsss. The only tradeoff is that the class needs to be specified, but that turns this into a two-liner.

<pre><code>import java.util.EnumSet;

public class HelloWorld {

static enum Choices {a1, a2, b1, b2}

public static &lt;E extends Enum&lt;E&gt;&gt; boolean contains(Class&lt;E&gt; _enumClass, String value) {
 try {
 return EnumSet.allOf(_enumClass).contains(Enum.valueOf(_enumClass, value)); 
 } catch (Exception e) {
 return false; 
 }
}

public static void main(String[] args) {
 for (String value : new String[] {"a1", "a3", null}) {
 System.out.println(contains(Choices.class, value));
 }
}
</code></pre>

}

blocks|key|1010057|text|com.google.common.collect.Sets.newHashSet(MyEnum.values()).contains("myValue")|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1010058|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>com.google.common.collect.Sets.newHashSet(MyEnum.values()).contains("myValue")
</code></pre>

blocks|key|1010198|text|检查值是否存在以及返回枚举值的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010199|protected+TradeType+getEnumType(String+tradeType)+{
++++if+(tradeType+!=+null)+{
++++++++if+(EnumUtils.isValidEnum(TradeType.class,+tradeType))+{
++++++++++++return+TradeType.valueOf(tradeType);
++++++++}
++++}
++++return+null;
}|code-block|syntax|javascript|1010200|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

solution to check whether value is present as well get enum value in return :

<pre><code>protected TradeType getEnumType(String tradeType) {
 if (tradeType != null) {
 if (EnumUtils.isValidEnum(TradeType.class, tradeType)) {
 return TradeType.valueOf(tradeType);
 }
 }
 return null;
}
</code></pre>

blocks|key|796212|text|++Set.of(CustomType.values())
+++++.contains(customTypevalue)+|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|796213|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> Set.of(CustomType.values())
 .contains(customTypevalue) 
</code></pre>

blocks|key|1010429|text|您还可以使用:+com.google.common.base.Enums|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010430|Enums.getIfPresent(varEnum.class，varToLookFor)返回可选的|1010431|Enums.getIfPresent(fooEnum.class，myVariable).isPresent()？Enums.getIfPresent(fooEnum.class，myVariable).get+:+fooEnum.OTHERS|1010432|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

you can also use : com.google.common.base.Enums

Enums.getIfPresent(varEnum.class, varToLookFor) returns an Optional

Enums.getIfPresent(fooEnum.class, myVariable).isPresent() ?
Enums.getIfPresent(fooEnum.class, myVariable).get : fooEnum.OTHERS

blocks|key|796374|text|如果您想导入Apache+commons+lang3，EnumUtils.isValidEnum可能是最好的选择。如果不是，下面是一个通用函数，我会将其用作替代函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|796375|private+<T+extends+Enum<T>>+boolean+enumValueExists(Class<T>+enumType,+String+value)+{
++++boolean+result;
++++try+{
++++++++Enum.valueOf(enumType,+value);
++++++++result+=+true;
++++}+catch+(IllegalArgumentException+e)+{
++++++++result+=+false;
++++}
++++return+result;
}|code-block|syntax|javascript|796376|并使用它，如下所示|796377|if+(enumValueExists(MyEnum.class,+configValue))+{
++++//+happy+code
}+else+{
++++//+angry+code
}|796378|entityMap^0|R|L|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

<code>EnumUtils.isValidEnum</code> might be the best option if you like to import Apache commons lang3. if not following is a generic function I would use as an alternative.
<pre><code>private &lt;T extends Enum&lt;T&gt;&gt; boolean enumValueExists(Class&lt;T&gt; enumType, String value) {
 boolean result;
 try {
 Enum.valueOf(enumType, value);
 result = true;
 } catch (IllegalArgumentException e) {
 result = false;
 }
 return result;
}

</code></pre>
And use it as following
<pre><code>if (enumValueExists(MyEnum.class, configValue)) {
 // happy code
} else {
 // angry code
}
</code></pre>

blocks|key|1010920|text|虽然在大多数情况下，迭代列表或捕获异常就足够了，但我正在寻找一些可重用的东西，可以很好地处理大型枚举。最后，我写了这样的代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1010921|public+class+EnumValidator+{

++++private+final+Set<String>+values;

++++private+EnumValidator(Set<String>+values)+{
++++++++this.values+=+values;
++++}

++++public+static+<T+extends+Enum<T>>+EnumValidator+of(Class<T>+enumType){
++++++++return+new+EnumValidator(Stream.of(enumType.getEnumConstants()).map(Enum::name).collect(Collectors.toSet()));
++++}

++++public+boolean+isPresent(String+et){
++++++++return+values.contains(et);
++++}
++++
}|code-block|syntax|javascript|1010922|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

While iterating a list or catching an exception is good enough for most cases I was searching for something reusable that works well for large enums. In it end, I end up writing this:
<pre><code>public class EnumValidator {

 private final Set&lt;String&gt; values;

 private EnumValidator(Set&lt;String&gt; values) {
 this.values = values;
 }

 public static &lt;T extends Enum&lt;T&gt;&gt; EnumValidator of(Class&lt;T&gt; enumType){
 return new EnumValidator(Stream.of(enumType.getEnumConstants()).map(Enum::name).collect(Collectors.toSet()));
 }

 public boolean isPresent(String et){
 return values.contains(et);
 }
 
}
</code></pre>

blocks|key|796453|text|Java+8%2B流%2B设置方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|796454|++++//+Build+the+set.
++++final+Set<String>+mySet+=+Arrays//
++++++.stream(YourEnumHere.values())//
++++++.map(Enum::name)//
++++++.collect(Collectors.toSet());

++++//+Reuse+the+set+for+contains+multiple+times.
++++mySet.contains(textA);
++++mySet.contains(textB);
++++...|code-block|syntax|javascript|796455|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Java 8+ stream + set way:
<pre><code> // Build the set.
 final Set&lt;String&gt; mySet = Arrays//
 .stream(YourEnumHere.values())//
 .map(Enum::name)//
 .collect(Collectors.toSet());

 // Reuse the set for contains multiple times.
 mySet.contains(textA);
 mySet.contains(textB);
 ...
</code></pre>

blocks|key|795388|text|public+boolean+contains(Choices+value)+{
+++return+EnumSet.allOf(Choices.class).contains(value);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|795389|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 boolean contains(Choices value) {
 return EnumSet.allOf(Choices.class).contains(value);
}
</code></pre>

blocks|key|795136|text|enum在Java中是相当强大的。您可以轻松地将contains方法添加到枚举中(就像将方法添加到类中一样)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|795137|enum+choices+{
++a1,+a2,+b1,+b2;

++public+boolean+contains(String+s)
++{
++++++if+(s.equals("a1")+%7C%7C+s.equals("a2")+%7C%7C+s.equals("b1")+%7C%7C+s.equals("b2"))+
+++++++++return+true;
++++++return+false;
++}+

};|code-block|syntax|javascript|795138|entityMap^0|0|4|O|8|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

<code>enum</code> are pretty powerful in Java. You could easily add a <code>contains</code> method to your enum (as you would add a method to a class):

<pre><code>enum choices {
 a1, a2, b1, b2;

 public boolean contains(String s)
 {
 if (s.equals("a1") || s.equals("a2") || s.equals("b1") || s.equals("b2")) 
 return true;
 return false;
 } 

};
</code></pre>

Here's my problem - I'm looking for (if it even exists) the enum equivalent of <code>ArrayList.contains();</code>.

Here's a sample of my code problem:

<pre><code>enum choices {a1, a2, b1, b2};

if(choices.???(a1)}{
//do this
} 
</code></pre>

Now, I realize that an <code>ArrayList</code> of <code>Strings</code> would be the better route here but I have to run my enum contents through a switch/case elsewhere. Hence my problem.

Assuming something like this doesn't exist, how could I go about doing it?

Java: Check if enum contains a given string?

Java

这就是我的问题--我正在寻找(如果它存在的话) ArrayList.contains();的枚举等价物。下面是我的代码问题的一个示例：enum choices {a1, a2, b1, b2};if(choices.???(a1)}{//do this} 现在，我意识到在这里使用Strings的ArrayList会更好，但我必须在其他地方通过开关/case来运行我的枚举内容。这就是我的问题所在。假

问Java:检查enum是否包含给定的字符串？
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回答 30

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问Java:检查enum是否包含给定的字符串？EN

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