Java枚举反向查找最佳实践

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Java枚举反向查找最佳实践

public enum Status {
    WAITING(0),
    READY(1),
    SKIPPED(-1),
    COMPLETED(5);
    private static final Map<Integer,Status> lookup 
            = new HashMap<Integer,Status>();
    static {
        for(Status s : EnumSet.allOf(Status.class))
            lookup.put(s.getCode(), s);
    private int code;
    private Status(int code) {
        this.code = code;
    public int getCode() { return code; }
    public static Status get(int code) { 
        return lookup.get(code); 
}

public enum Status {
    WAITING(0),
    READY(1),
    SKIPPED(-1),
    COMPLETED(5);
    private int code;
    private Status(int code) {
        this.code = code;
    public int getCode() { return code; }
    public static Status get(int code) { 
        for(Status s : values()) {
            if(s.code == code) return s;
        return null;
}

public enum MyEnum {
    A(0), B(1), C(2);
    private static final Map<Integer, MyEnum> LOOKUP = Maps.uniqueIndex(
                Arrays.asList(MyEnum.values()),
                MyEnum::getStatus
    private final int status;
    MyEnum(int status) {
        this.status = status;
    public int getStatus() {
        return status;
    @Nullable
    public static MyEnum fromStatus(int status) {
        return LOOKUP.get(status);
}

public enum Status {
    WAITING(0),
    READY(1),
    SKIPPED(-1),
    COMPLETED(5);
    private int code;
    private Status(int code) {
        this.code = code;
    public int getCode() { return code; }
    public static Status get(int code) {
        switch(code) {
            case  0: return WAITING;
            case  1: return READY;
            case -1: return SKIPPED;
            case  5: return COMPLETED;
        return null;
}

// DictionarySupport.java :
import org.apache.commons.collections4.Factory;
import org.apache.commons.collections4.map.LazyMap;
import java.util.HashMap;
import java.util.Map;
public interface DictionarySupport<T extends Enum<T>> {
    @SuppressWarnings("unchecked")
    Map<Class<?>,  Map<String, Object>> byCodeMap = LazyMap.lazyMap(new HashMap(), (Factory) HashMap::new);
    @SuppressWarnings("unchecked")
    Map<Class<?>,  Map<Object, String>> byEnumMap = LazyMap.lazyMap(new HashMap(), (Factory) HashMap::new);
    default void init(String code) {
        byCodeMap.get(this.getClass()).put(code, this);
        byEnumMap.get(this.getClass()).put(this, code) ;
    static <T extends Enum<T>> T getByCode(Class<T> clazz,  String code) {
        clazz.getEnumConstants();
        return (T) byCodeMap.get(clazz).get(code);
    default <T extends Enum<T>> String getCode() {
        return byEnumMap.get(this.getClass()).get(this);
// Dictionary 1:
public enum Dictionary1 implements DictionarySupport<Dictionary1> {
    VALUE1("code1"),
    VALUE2("code2");
    private Dictionary1(String code) {
        init(code);
// Dictionary 2:
public enum Dictionary2 implements DictionarySupport<Dictionary2> {
    VALUE1("code1"),
    VALUE2("code2");
    private Dictionary2(String code) {
        init(code);
// DictionarySupportTest.java:     
import org.testng.annotations.Test;
import static org.fest.assertions.api.Assertions.assertThat;
public class DictionarySupportTest {
    @Test
    public void teetSlownikSupport() {
        assertThat(getByCode(Dictionary1.class, "code1")).isEqualTo(Dictionary1.VALUE1);
        assertThat(Dictionary1.VALUE1.getCode()).isEqualTo("code1");
        assertThat(getByCode(Dictionary1.class, "code2")).isEqualTo(Dictionary1.VALUE2);
        assertThat(Dictionary1.VALUE2.getCode()).isEqualTo("code2");
        assertThat(getByCode(Dictionary2.class, "code1")).isEqualTo(Dictionary2.VALUE1);
        assertThat(Dictionary2.VALUE1.getCode()).isEqualTo("code1");
        assertThat(getByCode(Dictionary2.class, "code2")).isEqualTo(Dictionary2.VALUE2);
        assertThat(Dictionary2.VALUE2.getCode()).isEqualTo("code2");
}

public static Optional<Status> of(int value) {
    return Arrays.stream(values()).filter(v -> value == v.getCode()).findFirst();
}

@AllArgsConstructor
@Getter
public enum MyEnum {
    A(0),
    B(1),
    C(2);
    private static final Map<Integer, MyEnum> LOOKUP =
            Arrays.stream(MyEnum.values()).collect(Collectors.toMap(MyEnum::getStatus, Function.identity()));
    private final int status;

Java枚举反向查找最佳实践

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