CODEWITHSUNDEEP
javac#mongodbuuidguid
YABADABADOU
YABADABADOU

Reputation: 1328

Transforming a Java UUID object to a .NET GUID string

In a Java method that receives a java.util.UUID Object, I would like to display this object as a string in the .NET/C# format (CSUUID).

Currently I am only able to display it in the Java format (JUUID) :

static String GetStringFromUuid (java.util.UUID myUuid){
    return myUuid.toString();
}

Current output: "46c7220b-1f25-0118-f013-03bd2c22d6b8"

Desired output: "1f250118-220b-46c7-b8d6-222cbd0313f0"

Context:

Upvotes: 4

Views: 3567

Answers (2)

Evk
Evk

Reputation: 101473

Guid is represented by 16 bytes. For various reasons, both Java and .NET do not just print those bytes in order when you call toString. For example, if we look at base-64 encoded guid from your question:

GAElHwsix0a41iIsvQMT8A==

In hex form it will look like this:

18-01-25-1f-0b-22-c7-46-b8-d6-22-2c-bd-03-13-f0

Java toString produces this (if we format as above):

46-c7-22-0b-1f-25-01-18-f0-13-03-bd-2c-22-d6-b8

.NET ToString produces this:

1f-25-01-18-22-0b-46-c7-b8-d6-22-2c-bd-03-13-f0

If you look at this for some time - you will notice that both java and .NET strings represent the same 16 bytes, but positions of those bytes in output string are different. So to convert from java representation to .NET you just need to reorder them. Sample code (I don't know java, so probably it could be done in a better way, but still should achieve the desired result):

static String GetStringFromUuid (java.util.UUID myUuid){
    byte[] bytes = new byte[16];
    // convert uuid to byte array
    ByteBuffer bb = ByteBuffer.wrap(bytes);
    bb.putLong(myUuid.getMostSignificantBits());
    bb.putLong(myUuid.getLeastSignificantBits());
    // reorder
    return String.format("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
        bytes[4],bytes[5],bytes[6],bytes[7],
        bytes[2],bytes[3],bytes[0],bytes[1],
        bytes[15],bytes[14],bytes[13],bytes[12],
        bytes[11],bytes[10],bytes[9],bytes[8]);
}

Upvotes: 6

Nishanth
Nishanth

Reputation: 835

We can just keep the GUID as string, if the c# function is receiving the string and it needs to be displayed or sent to some service as string

Just in case if you want to parse it. You can use the link for GUID parsing logic example

For creating new GUID in C#, use

var guid = System.Guid.NewGuid();
var guidString = guid.ToString();

For creating new UUID in Java, use

UUID uuid = java.util.UUID.randomUUID();
String uuidString = uuid.toString();

Upvotes: 1

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