Java cast Long to Enum type issue

Question

I had a little problem with casting Java long type to Enum type and can't find a solution how to do that.

Here is what I'm using :

public enum DataType {
    IMAGES(1),
    VIDEOS(2);

    private int value;
    private DataType(int i){
        this.value = i;
    }
}

and I need to do something like this:

DataType dataType;
String thiz = "1";
long numb = Long.parseLong(thiz);
dataType = numb;

The error that I get says:

Convert numb to DataType or convert dataType to long.

Second Scenario:

I have this :

static String[] packetType;
String tmp=incomingData.toString(); // where incomingData is byte[]
int lastLoc = 0;
int needsSize = packetFieldSizes[tmpCurrentField-1]; // where packetFieldSizes,tmpCurrentField are integers.
thiz=tmp.substring(lastLoc, needsSize);    

packetType=thiz;  // packetType = thiz copy; where thiz is the same as used above.

I tried to convert thiz to String[] and use valueOf,but

Any suggestions how to get the thinks to work?

Thanks in advance!

Answer 1

Enum already provides a unique integer for each of it's instances. Check out ordinal(). (Note that it's zero-based though.)

If you need to go from a long to a DataType you can do

DataType dataType;
String thiz;
long numb = Long.parseLong(thiz);
dataType = DataType.values()[(int) numb];

A complete list of conversions from and to enum constants, strings and integers can be found in this answer:

• Conveniently map between enum and int / String

Answer 2

If for some reason you need to assign the numbers yourself and thereby can't use aioobe's good solution, you can do something like the following:

public enum DataType {
    IMAGES(1),
    VIDEOS(2);

 private final int value;
 private DataType(int i){
    this.value=i;
 }
 public static DataType getByValue(int i) {
     for(DataType dt : DataType.values()) {
         if(dt.value == i) {
             return dt;
         }
     }
     throw new IllegalArgumentException("no datatype with " + i + " exists");
 }

The static method getByValue() searches for the DataType with the provided number.