将整数值转换为匹配的Java Enum [英] Convert integer value to matching Java Enum

问题描述

我有这样的枚举：

public enum PcapLinkType {
  DLT_NULL(0)
  DLT_EN10MB(1)
  DLT_EN3MB(2),
  DLT_AX25(3),
  /*snip, 200 more enums, not always consecutive.*/
  DLT_UNKNOWN(-1);
    private final int value;   

    PcapLinkType(int value) {
        this.value= value;
    }
}

现在我从外部输入获得一个int并希望匹配输入 - 如果值不存在则抛出异常是可以的，但在这种情况下我最好是 DLT_UNKNOWN 。

Now I get an int from external input and want the matching input - throwing an exception if a value does not exist is ok, but preferably I'd have it be DLT_UNKNOWN in that case.

int val = in.readInt();
PcapLinkType type = ???; /*convert val to a PcapLinkType */

推荐答案

你会需要手动执行此操作，方法是在将整数映射到枚举的类中添加静态映射，例如

You would need to do this manually, by adding a a static map in the class that maps Integers to enums, such as

private static final Map<Integer, PcapLinkType> intToTypeMap = new HashMap<Integer, PcapLinkType>();
static {
    for (PcapLinkType type : PcapLinkType.values()) {
        intToTypeMap.put(type.value, type);
    }
}

public static PcapLinkType fromInt(int i) {
    PcapLinkType type = intToTypeMap.get(Integer.valueOf(i));
    if (type == null) 
        return PcapLinkType.DLT_UNKNOWN;
    return type;
}

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