java - How to get the enum type by its attribute?

Question

I have written an enum class and I want to either get the attribute by type or get the type by attribute, but it seems impossible.

public enum AreaCode {
    area1(7927),
    area2(7928),
    area3(7929);

    private final int ac;

    AreaCode(int ac) {
        this.ac = ac;
    }

    int areaCode(){
        return ac;
    }

    AreaCode area(int n) {
        switch (n) {
            case 7927: return AreaCode.area1;
            case 7928: return AreaCode.area2;
            case 7929: return AreaCode.area3;
        }
    }
}

The code above will not compile. How to make area(int n) work?

Answer 1

Apart from the issues pointed at by the other posters, I'd rewrite the method to avoid duplicating the information (keep it DRY!):

public static AreaCode area(int n) {
  for (AreaCode c : values()) {
    if (c.ac == n) {
      return c;
    }
  }
  // either throw the IAE or return null, your choice.
  throw new IllegalArgumentException(String.valueOf(n));
}