blocks|key|622832|text|尝尝这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|622833|Months.values()[index]|code-block|syntax|javascript|622834|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|$]]

Try this

<pre><code>Months.values()[index]
</code></pre>

blocks|key|622850|text|这里有三种方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|622851|public+enum+Months+{
++++JAN(1),+FEB(2),+MAR(3),+APR(4),+MAY(5),+JUN(6),+JUL(7),+AUG(8),+SEP(9),+OCT(10),+NOV(11),+DEC(12);


++++int+monthOrdinal+=+0;

++++Months(int+ord)+{
++++++++this.monthOrdinal+=+ord;
++++}

++++public+static+Months+byOrdinal2ndWay(int+ord)+{
++++++++return+Months.values()[ord-1];+//+less+safe
++++}

++++public+static+Months+byOrdinal(int+ord)+{
++++++++for+(Months+m+:+Months.values())+{
++++++++++++if+(m.monthOrdinal+==+ord)+{
++++++++++++++++return+m;
++++++++++++}
++++++++}
++++++++return+null;
++++}
++++public+static+Months[]+MONTHS_INDEXED+=+new+Months[]+{+null,+JAN,+FEB,+MAR,+APR,+MAY,+JUN,+JUL,+AUG,+SEP,+OCT,+NOV,+DEC+};

}




import+static+junit.framework.Assert.assertEquals;

import+org.junit.Test;

public+class+MonthsTest+{

@Test
public+void+test_indexed_access()+{
++++assertEquals(Months.MONTHS_INDEXED[1],+Months.JAN);
++++assertEquals(Months.MONTHS_INDEXED[2],+Months.FEB);

++++assertEquals(Months.byOrdinal(1),+Months.JAN);
++++assertEquals(Months.byOrdinal(2),+Months.FEB);


++++assertEquals(Months.byOrdinal2ndWay(1),+Months.JAN);
++++assertEquals(Months.byOrdinal2ndWay(2),+Months.FEB);
}

}|code-block|syntax|javascript|622852|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|$]]

Here's three ways to do it.

<pre><code>public enum Months {
 JAN(1), FEB(2), MAR(3), APR(4), MAY(5), JUN(6), JUL(7), AUG(8), SEP(9), OCT(10), NOV(11), DEC(12);


 int monthOrdinal = 0;

 Months(int ord) {
 this.monthOrdinal = ord;
 }

 public static Months byOrdinal2ndWay(int ord) {
 return Months.values()[ord-1]; // less safe
 }

 public static Months byOrdinal(int ord) {
 for (Months m : Months.values()) {
 if (m.monthOrdinal == ord) {
 return m;
 }
 }
 return null;
 }
 public static Months[] MONTHS_INDEXED = new Months[] { null, JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC };

}




import static junit.framework.Assert.assertEquals;

import org.junit.Test;

public class MonthsTest {

@Test
public void test_indexed_access() {
 assertEquals(Months.MONTHS_INDEXED[1], Months.JAN);
 assertEquals(Months.MONTHS_INDEXED[2], Months.FEB);

 assertEquals(Months.byOrdinal(1), Months.JAN);
 assertEquals(Months.byOrdinal(2), Months.FEB);


 assertEquals(Months.byOrdinal2ndWay(1), Months.JAN);
 assertEquals(Months.byOrdinal2ndWay(2), Months.FEB);
}

}
</code></pre>

blocks|key|838697|text|我只是尝试了同样的方法，并提出了以下解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|838698|public+enum+Countries+{
++++TEXAS,
++++FLORIDA,
++++OKLAHOMA,
++++KENTUCKY;

++++private+static+Countries[]+list+=+Countries.values();

++++public+static+Countries+getCountry(int+i)+{
++++++++return+list[i];
++++}

++++public+static+int+listGetLastIndex()+{
++++++++return+list.length+-+1;
++++}
}|code-block|syntax|javascript|838699|该类将自己的值保存在一个数组中，我使用该数组来获取indexposition处的枚举。如上所述，数组从0开始计数，如果您希望索引从'1‘开始，只需将这两个方法更改为：|838700|public+static+String+getCountry(int+i)+{
++++return+list[(i+-+1)];
}

public+static+int+listGetLastIndex()+{
++++return+list.length;
}|838701|在我的Main中，我使用以下命令获取所需的countries+object|838702|public+static+void+main(String[]+args)+{
+++int+i+=+Countries.listGetLastIndex();
+++Countries+currCountry+=+Countries.getCountry(i);
}|838703|它将currCountry设置为最后一个国家/地区，在本例中为Countries.KENTUCKY。|838704|请记住，如果您使用硬编码的索引来获取对象，则此代码会受到ArrayOutOfBoundsExceptions的严重影响。|838705|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

I just tried the same and came up with following solution:

<pre><code>public enum Countries {
 TEXAS,
 FLORIDA,
 OKLAHOMA,
 KENTUCKY;

 private static Countries[] list = Countries.values();

 public static Countries getCountry(int i) {
 return list[i];
 }

 public static int listGetLastIndex() {
 return list.length - 1;
 }
}
</code></pre>

The class has it's own values saved inside an array, and I use the array to get the enum at indexposition. As mentioned above arrays begin to count from 0, if you want your index to start from '1' simply change these two methods to:

<pre><code>public static String getCountry(int i) {
 return list[(i - 1)];
}

public static int listGetLastIndex() {
 return list.length;
}
</code></pre>

Inside my Main I get the needed countries-object with 

<pre><code>public static void main(String[] args) {
 int i = Countries.listGetLastIndex();
 Countries currCountry = Countries.getCountry(i);
}
</code></pre>

which sets currCountry to the last country, in this case Countries.KENTUCKY.

Just remember this code is very affected by ArrayOutOfBoundsExceptions if you're using hardcoded indicies to get your objects.

blocks|key|838757|text|我最近遇到了同样的问题，并使用了Harry+Joy提供的解决方案。不过，该解决方案只适用于从零开始的枚举。我也不会考虑它，因为它不处理超出范围的索引。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|838758|我最终使用的解决方案可能没有那么简单，但它是完全节省的，即使使用大枚举也不会影响代码的性能：|838759|public+enum+Example+{

++++UNKNOWN(0,+"unknown"),+ENUM1(1,+"enum1"),+ENUM2(2,+"enum2"),+ENUM3(3,+"enum3");

++++private+static+HashMap<Integer,+Example>+enumById+=+new+HashMap<>();
++++static+{
++++++++Arrays.stream(values()).forEach(e+->+enumById.put(e.getId(),+e));
++++}

++++public+static+Example+getById(int+id)+{
++++++++return+enumById.getOrDefault(id,+UNKNOWN);
++++}

++++private+int+id;
++++private+String+description;

++++private+Example(int+id,+String+description)+{
++++++++this.id+=+id;
++++++++this.description=+description;
++++}

++++public+String+getDescription()+{
++++++++return+description;
++++}

++++public+int+getId()+{
++++++++return+id;
++++}
}|code-block|syntax|javascript|838760|如果您确定您的索引永远不会超出范围，并且您不想像我上面那样使用UNKNOWN，那么您当然也可以这样做：|offset|length|style|CODE|838761|public+static+Example+getById(int+id)+{
++++++++return+enumById.get(id);
}|838762|entityMap^0|0|0|0|V|7|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@$K|W|L|X|M|N]]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I recently had the same problem and used the solution provided by Harry Joy. 
That solution only works with with zero-based enumaration though. I also wouldn't consider it save as it doesn't deal with indexes that are out of range.

The solution I ended up using might not be as simple but it's completely save and won't hurt the performance of your code even with big enums:

<pre><code>public enum Example {

 UNKNOWN(0, "unknown"), ENUM1(1, "enum1"), ENUM2(2, "enum2"), ENUM3(3, "enum3");

 private static HashMap&lt;Integer, Example&gt; enumById = new HashMap&lt;&gt;();
 static {
 Arrays.stream(values()).forEach(e -&gt; enumById.put(e.getId(), e));
 }

 public static Example getById(int id) {
 return enumById.getOrDefault(id, UNKNOWN);
 }

 private int id;
 private String description;

 private Example(int id, String description) {
 this.id = id;
 this.description= description;
 }

 public String getDescription() {
 return description;
 }

 public int getId() {
 return id;
 }
}
</code></pre>

If you are sure that you will never be out of range with your index and you don't want to use <code>UNKNOWN</code> like I did above you can of course also do:

<pre><code>public static Example getById(int id) {
 return enumById.get(id);
}
</code></pre>

I have an enum in Java:

<pre><code>public enum Months
{
 JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC
}
</code></pre>

I want to access enum values by index, e.g.

<pre><code>Months(1) = JAN;
Months(2) = FEB;
...
</code></pre>

How shall I do that?

How to get Enum Value from index in Java?

Java

我在Java中有一个枚举：public enum Months{    JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC}我想按索引访问枚举值，例如Months(1) = JAN;Months(2) = FEB;...我该怎么做呢？

问在Java中如何从索引中获取枚举值？
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