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Java枚举反向查找

enums java

Zed · 技术社区 · 7 年前

所以我有一个枚举,它不能像我预期的那样工作,需要进行一些修改:

public enum MyEnum {

    CODE000("text description comes here"),

    private final String value;

    private static final Map<String, MyEnum> LOOKUP = Maps.uniqueIndex(
            Arrays.asList(MyEnum.values()),
            MyEnum::getValue
    );

    MyEnum(final String value) {
        this.value = value;
    }

    public String getValue() {
        return value;

    }


    public static MyEnum fromStatus(String status) {
        return LOOKUP.get(status);
    }
}

它现在的工作方式是:

MyEnum.fromStatus("text description comes here") 当然,我想换一种方式:

MyEnum.fromStatus("CODE000") 把我还给你 "text description comes here"

有人能建议我怎么改这个吗?

4 回复 | 直到 7 年前

ernest_k Petronella 7 年前

valueOf

MyEnum code000 =  MyEnum.valueOf("CODE000");

String val = code000.getValue();

MyEnum

Thiyagu 7 年前

MyEnum::getValue MyEnum::name

MyEnum getValue

Omid Nazerizadeh 7 年前

public static String fromStatus(String status) {
    MyEnum myEnum = valueOf(status);

    return myEnum.getValue();
}

LuCio 7 年前

valueOf IllegalArgumentException

Maps null

  public static MyEnum fromStatus(String status) { ... }

  public static String fromStatus(String name) { ... }

MyEnum.fromStatus("CODE000") fromName MyEnum

public enum MyEnum {

  CODE000("text description comes here");

  private final String value;

  private static final Map<String, MyEnum> LOOKUP_ENUM = Maps.uniqueIndex(Arrays.asList(MyEnum.values()), MyEnum::getValue);
  private static final Map<String, String> LOOKUP_STATUS = Arrays.stream(MyEnum.values()).collect(Collectors.toMap(MyEnum::name, MyEnum::getValue));

  MyEnum(final String value) {
    this.value = value;
  }

  public String getValue() {
    return value;

  }

  public static MyEnum fromStatus(String status) {
    return LOOKUP_ENUM.get(status);
  }

  public static String fromName(String name) {
    return LOOKUP_STATUS.get(name);
  }

}

  private static final Map<String, MyEnum> LOOKUP = Maps.uniqueIndex(Arrays.asList(MyEnum.values()), MyEnum::name);

  public static MyEnum byName(String name) {
    return LOOKUP.get(name);
  }

System.out.println(MyEnum.fromStatus("text description comes here")); // CODE000
System.out.println(MyEnum.fromStatus("invalid")); // null - no exception
System.out.println(MyEnum.fromStatus(null)); // null - no exception

System.out.println(MyEnum.fromName("CODE000")); // "text description comes here"
System.out.println(MyEnum.fromName("invalid")); // null - no exception
System.out.println(MyEnum.fromName(null)); // null - no exception

System.out.println(MyEnum.byName("CODE000")); // CODE000
System.out.println(MyEnum.byName("invalid")); // null - no exception
System.out.println(MyEnum.byName(null)); // null - no exception

byName statusByName

Optional<String> Optional<MyEnum>

  public static Optional<MyEnum> fromStatus(String status) { ... }
  public static Optional<String> statusByName(String name) { ... }
  public static Optional<MyEnum> byName(String name) { ... }