How to convert Mac to string?

How do I convert the MAC data type to String? I am able to use base64 to encode the SecretKey data type into a String but this doesn't work for MAC. 

// Generate a secret MAC key

KeyGenerator kg = KeyGenerator.getInstance("HmacSHA1");  
SecretKey key = kg.generateKey();
String encodedkey=Base64.getEncoder().encodeToString(key.getEncoded());


// Create and initialize a MAC with the key
Mac mac = Mac.getInstance("HmacSHA1");
mac.init(key);

// Print the key

System.out.println("Key:" + encodedkey);

// Print out the resulting MAC

System.out.println("MAC:" + mac);

My output

Key:lnGahJHeKDqMG+c/K8OHx9HiQQl+aqhCNb0QtnDAdhzE3Xs7gP0uXf93ESO9Demrnl0XFCqHVUBsU9oppkmgVQ==
MAC:javax.crypto.Mac@1ce92674

Desired sample output

Key: lqC5SNoKYPnQRVFxTp2YhvBQpWiZU7sWTjziVXgMmcFkxvBJQA81PoTqrvscOyj05pvm6MBtlvP6gkqJvisiNQ==
MAC: xca73kbvEEZBKwb0aWMhGA==
Jon Skeet
people
quotationmark

The Mac class itself isn't the data - it holds the data and updates it on calls to update and doFinal.

Currently you're only calling init with the key - you then need to call update (optionally) and then doFinal. When you call doFinal, that will return a byte[] of the actual hash. Currently we can't see any data that you want to hash, but your sample would be changed like this:

Mac mac = Mac.getInstance("HmacSHA1");
mac.init(key);
mac.update(data1);
mac.update(data2);
mac.update(data3);
// Etc...
byte[] hash = mac.doFinal();
String base64Hash = Base64.getEncoder().encodeToString(hash);

You can also call doFinal passing in data - if you only have a single piece of data to hash, this means you don't need to call update at all:

Mac mac = Mac.getInstance("HmacSHA1");
mac.init(key);
byte[] hash = mac.doFinal(data);
String base64Hash = Base64.getEncoder().encodeToString(hash);

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