我正在尝试创建一个场景,其中通过enum class A
中的枚举常量将子enum class B
和包含自己的常量enum class C
相关联。enum class B
中的常量和 enum class C
组中的常量是 enum class D
中的常量子集。以下是我想要实现的基本目标:
enum A {
CONST_1 ("const_1", B), // B is the associated enum
CONST_2 ("const_2", C); // C in the associated enum
private final String strVal;
private final Enum associatedEnum;
private A (String strVal, Enum associatedEnum) {
this.strVal = strVal;
this.associatedEnum = associatedEnum;
}
public Enum getAssociatedEnum() {
return this.associatedEnum;
}
public String toString() {
return this.strVal;
}
// Associated Enum contained subset of grouped constants
enum B {
CONST_3 (D.CONST_7.toString()),
CONST_4 (D.CONST_8.toString());
private final String strVal;
private B (String strVal) {
this.strVal = strVal;
}
public String toString() {
return this.strVal;
}
}
// Associated Enum contained subset of grouped constants
enum C {
CONST_5 (D.CONST_9.toString()),
CONST_6 (D.CONST_10.toString());
private final String strVal;
private C (String strVal) {
this.strVal = strVal;
}
public String toString() {
return this.strVal;
}
}
}
// Separate Enum containing all ungrouped constants
enum D {
CONST_7 ("const_7"),
CONST_8 ("const_8");
CONST_9 ("const_9"),
CONST_10 ("const_10");
private final String strVal;
private D (String strVal) {
this.strVal = strVal;
}
public String toString() {
return this.strVal;
}
}
显然,这种语法在 OOTB 中不起作用,因为您无法以这种方式在 Java 中传递类。但是谁能提出一种可以实现这一目标的方法?
我希望使用它来验证客户端应用程序中的静态结构化分组。
这应该有希望做你想要的。我包含一个示例用法,它将列出子枚举类型值。
package a.b.c;
public class EnumsTest {
public enum A {
A1( B.class ),
A2( C.class );
private final Class<? extends Enum<?>> enumClazz;
A( final Class<? extends Enum<?>> enumClazz ) {
this.enumClazz = enumClazz;
}
public Enum<?>[] getSubEnumConstants() {
return enumClazz.getEnumConstants();
}
/**
* @param value
* @return Never null
* @throws IllegalArgumentException To be consistent with Enum.valueOf()
*/
public <T> Enum<?> valueOfSubEnum( final String value ) throws IllegalArgumentException {
for( Enum<?> enumInstance : getSubEnumConstants() ) {
if( enumInstance.name().equals( value ) ) {
return enumInstance;
}
}
throw new IllegalArgumentException( "valueOf for " + enumClazz.getName() + " could not be resoled with the value of " + value );
}
}
public enum B {
B1,
B2;
}
public enum C {
C1,
C2;
}
public static void main( String[] args ) {
for( A a : A.values() ) {
for( Enum<?> enumInstance : a.getSubEnumConstants() ) {
System.out.println( a.name() + ":" + enumInstance.name() );
}
}
Enum<?> valueOfSubEnum = A.A1.valueOfSubEnum( "B2" );
System.out.println( valueOfSubEnum.name() );
}
}
注: 如果要将子类型锁定到特定集,则可以使它们实现接口。
不能使用构造函数private B (String strVal, Enum associatedEnum)
声明enum A
。你可以在彼此内部声明其他枚举,但不能这样。
这对我有用,但我可能错过了您要实现的目标:
public enum A {
A1(B.B1),
A2(C.C2);
private final Enum<?> e;
private A(Enum<?> e) {
this.e = e;
}
static enum B {
B1,
B2;
}
static enum C {
C1(D.D1.getId()),
C2(D.D2.getId());
private String id;
private C(String id) {
this.id = id;
}
}
}
enum D {
D1("abc"),
D2("def");
private final String id;
private D(String id) {
this.id = id;
}
public String getId() {
return id;
}
}