我可以在Java枚举中添加一个返回方法吗？

Question

可以像这样在Android中使用Enum吗？

public enum EventAction 
{
  SDCARD_MOUNTED
  {
    public String toString() {
      return "External SDCard was mounted";
    }

    public int getCode() {
      return 25;
    }
  }
}  

从外部代码我只能访问EventAction.SDCARD_MOUNTED.toString(),但.getCode()不可见.我看到的示例显示了如何从代码内部使用getCode().

Answer 1

声明getCode()为abstract方法:

public enum EventAction 
{
  SDCARD_MOUNTED
  {
    @Override
    public String toString() {
      return "External SDCard was mounted";
    }
    @Override
    public int getCode() {
      return 25;
    }
  };

  public abstract int getCode();

}

如果每个值都以相同的方式实现,那么更清楚:

public enum EventAction {
  SDCARD_MOUNTED(25, "External SDCard was mounted");
  private final int code;
  private final String message;
  private EventAction(int code, String message) {
    this.code = code;
    this.message = message;
  }
  @Override
  public String toString() { return message; }
  public int getCode() { return code; }
}

Answer 2

您需要在枚举级别声明方法:

public enum EventAction 
{
  SDCARD_MOUNTED
  {
    public String toString() {
      return "External SDCard was mounted";
    }

    public int getCode() {
      return 25;
    }
  };

  public abstract int getCode();

}