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;
    }
}

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

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;
}

enum MyEnum {
    FIRST, SECOND, THIRD;
    private static MyEnum[] allValues = values();
    public static MyEnum fromOrdinal(int n) {return allValues[n];}
}

public static PcapLinkType forCode(int code) {
    for (PcapLinkType typе : PcapLinkType.values()) {
        if (type.getValue() == code) {
            return type
        }
    }
    return null;
 }

public enum PcapLinkType {
  DLT_NULL(0)
  DLT_EN10MB(1)
  DLT_EN3MB(2),
  DLT_AX25(3),
  DLT_UNKNOWN(-1);

    private final int value;

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

PcapLinkType type = PcapLinkType.values()[1]; /*convert val to a PcapLinkType */

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 static final Map<Integer, PcapLinkType> typesByValue = new HashMap<Integer, PcapLinkType>();

    static {
        for (PcapLinkType type : PcapLinkType.values()) {
            typesByValue.put(type.value, type);
        }
    }

    private final int value;

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

    public static PcapLinkType forValue(int value) {
        return typesByValue.get(value);
    }
}

static {
    for (PcapLinkType type : PcapLinkType.values()) {
        intToTypeMap.put(type.getValue(), type);
    }
}

public enum Quality {ENOUGH,BETTER,BEST;
                     private static final int amount = EnumSet.allOf(Quality.class).size();
                     private static Quality[] val = new Quality[amount];
                     static{ for(Quality q:EnumSet.allOf(Quality.class)){ val[q.ordinal()]=q; } }
                     public static Quality fromInt(int i) { return val[i]; }
                     public Quality next() { return fromInt((ordinal()+1)%amount); }
                    }

public static PcapLinkType of(int linkType) {

    switch (linkType) {
        case -1: return DLT_UNKNOWN
        case 0: return DLT_NULL;

        //ETC....

        default: return null;

    }
}

static final PcapLinkType[] values  = { DLT_NULL, DLT_EN10MB, DLT_EN3MB, null ...}

...

public static PcapLinkType  getPcapLinkTypeForInt(int num){
    try{
       return values[int];
    }catch(ArrayIndexOutOfBoundsException e){
       return DLT_UKNOWN;
    }
}