通过枚举的构造函数值获取枚举

Question

What is the right way of getting the enum by it's constructor value in java? Here's an example:

public enum Status{
CREATED("created"), IN_PROGRESS("inProgress"), COMPLETED("completed");

public final String statusStr;
Status(String statusStr){
  this.statusStr = statusStr;
}
}

So if the input I get is a string of 'created' how do I get Status.CREATED from it?

Answer 1

I don't think you can do it automatically. You will have to create a static method for that:

public static Status fromString(String string) {
    for (Status status : values()) {
        if (status.statusStr.equals(string)) {
            return status;
        }
    }
    throw new IllegalArgumentException(string);
}

Incorporating @Pshemo's suggestions, the code could also be:

@RequiredArgsConstructor @Getter
public enum Status {
    CREATED("created"), IN_PROGRESS("inProgress"), COMPLETED("completed");

    private static final Map<String, Status> MAP = Arrays.stream(Status.values())
            .collect(Collectors.toMap(Status::getStatusStr, Function.identity()));

    private final String statusStr;

    public static Status fromString(String string) {
        return Objects.requireNonNull(MAP.get(string));
    }
}