如何将值转换为枚举？ [英] How can I convert from a value to an enum?

问题描述

我有一个这样的枚举：

public enum Numbers {
  ONE(1), TWO(2), THREE(3);

  public final int num;

  public Numbers(int num) {
    this.num = num;
  }
}

我想要能够从参数转换为枚举，例如从int 1 到枚举 ONE 。在Java Enums中有内置的机制吗？或者我必须为自己编写自己的逻辑？

I want to be able to convert from argument to enum, for instance from the int 1 to the enum ONE. Is there any built-in mechanism in Java Enums to do this, or do I have to write my own logic for it?

推荐答案

是的，您必须编写自己的逻辑，因为 num 变量是您自己逻辑的一部分：

Yes you have to write your own logic as the num variable is a part of your own logic :

public enum Numbers {
    ONE(1), TWO(2), THREE(3);

    public final int num;

    private Numbers(int num) {
        this.num = num;
    }

    public static Numbers getNumber(int i){
        for(Numbers number : Numbers.values()){
            if(i == number.num){
                return number;
            }
        }
        throw new IllegalArgumentException("This number doesn't exist");
    }
}

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