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Add EnumUtils.getEnumMap(Class, Function). #730. 

Provides a different implementation than #730.
This commit is contained in:
Gary Gregory 2021-11-19 09:16:03 -05:00
parent 70abafc95d
commit 8a4d1b82f8
3 changed files with 72 additions and 6 deletions
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1
src/changes/changes.xml
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@ -101,6 +101,7 @@ The <action> type attribute can be add,update,fix,remove.
<action type="add" dev="ggregory" due-to="Gary Gregory">Add Streams.toStream(Collection).</action>
<action type="add" dev="ggregory" due-to="Gary Gregory">Add Streams.failableStream(Collection) and deprecate misnamed stream(Collection).</action>
<action type="add" dev="ggregory" due-to="Gary Gregory">Add Streams.failableStream(Stream) and deprecate misnamed stream(Stream).</action>
<action type="add" dev="ggregory" due-to="Maxwell Cody, Gary Gregory">Add EnumUtils.getEnumMap(Class, Function). #730</action>
<!-- UPDATE -->
<action type="update" dev="ggregory" due-to="Dependabot, Gary Gregory">Bump spotbugs-maven-plugin from 4.2.0 to 4.4.2.2 #735, #808, #822.</action>
<action type="update" dev="ggregory" due-to="Dependabot, XenoAmess">Bump Bump actions/cache from v2.1.4 to v2.1.6 #742, #752, #764.</action>

29
src/main/java/org/apache/commons/lang3/EnumUtils.java
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@ -20,10 +20,11 @@ import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.EnumSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* <p>Utility library to provide helper methods for Java enums.</p>
@ -281,11 +282,27 @@ public class EnumUtils {
* @return the modifiable map of enum names to enums, never null
*/
public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) {
final Map<String, E> map = new LinkedHashMap<>();
for (final E e: enumClass.getEnumConstants()) {
map.put(e.name(), e);
}
return map;
return getEnumMap(enumClass, E::name);
}
/**
* <p>
* Gets the {@code Map} of enums by name.
* </p>
*
* <p>
* This method is useful when you need a map of enums by name.
* </p>
*
* @param <E> the type of enumeration
* @param <K> the type of the map key
* @param enumClass the class of the enum to query, not null
* @param keyFunction the function to query for the key, not null
* @return the modifiable map of enums, never null
* @since 3.13.0
*/
public static <E extends Enum<E>, K> Map<K, E> getEnumMap(final Class<E> enumClass, final Function<E, K> keyFunction) {
return Stream.of(enumClass.getEnumConstants()).collect(Collectors.toMap(keyFunction::apply, Function.identity()));
}
/**

48
src/test/java/org/apache/commons/lang3/EnumUtilsTest.java
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@ -342,6 +342,40 @@ public class EnumUtilsTest {
assertFalse(test.containsKey("PURPLE"));
}
@Test
public void test_getEnumMap_keyFunction() {
final Map<Integer, Month> test = EnumUtils.getEnumMap(Month.class, Month::getId);
assertEquals("{1=JAN, 2=FEB, 3=MAR, 4=APR, 5=MAY, 6=JUN, 7=JUL, 8=AUG, 9=SEP, 10=OCT, 11=NOV, 12=DEC}", test.toString(),
"getEnumMap not created correctly");
assertEquals(12, test.size());
assertFalse(test.containsKey(0));
assertTrue(test.containsKey(1));
assertEquals(Month.JAN, test.get(1));
assertTrue(test.containsKey(2));
assertEquals(Month.FEB, test.get(2));
assertTrue(test.containsKey(3));
assertEquals(Month.MAR, test.get(3));
assertTrue(test.containsKey(4));
assertEquals(Month.APR, test.get(4));
assertTrue(test.containsKey(5));
assertEquals(Month.MAY, test.get(5));
assertTrue(test.containsKey(6));
assertEquals(Month.JUN, test.get(6));
assertTrue(test.containsKey(7));
assertEquals(Month.JUL, test.get(7));
assertTrue(test.containsKey(8));
assertEquals(Month.AUG, test.get(8));
assertTrue(test.containsKey(9));
assertEquals(Month.SEP, test.get(9));
assertTrue(test.containsKey(10));
assertEquals(Month.OCT, test.get(10));
assertTrue(test.containsKey(11));
assertEquals(Month.NOV, test.get(11));
assertTrue(test.containsKey(12));
assertEquals(Month.DEC, test.get(12));
assertFalse(test.containsKey(13));
}
@Test
public void test_getEnumSystemProperty() {
final String key = getClass().getName();
@ -531,6 +565,20 @@ public class EnumUtilsTest {
}
enum Month {
JAN(1), FEB(2), MAR(3), APR(4), MAY(5), JUN(6), JUL(7), AUG(8), SEP(9), OCT(10), NOV(11), DEC(12);
private final int id;
Month(int id) {
this.id = id;
}
public int getId() {
return this.id;
}
}
enum TooMany {
A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, A1, B1, C1, D1, E1, F1, G1, H1, I1,
J1, K1, L1, M1, N1, O1, P1, Q1, R1, S1, T1, U1, V1, W1, X1, Y1, Z1, A2, B2, C2, D2, E2, F2, G2, H2, I2, J2, K2, L2,