Question

I have an ArrayList of objects being dumped to a YAML string and have been comparing the performance of JYaml and SnakeYaml in handling this.

    ArrayList<HashMap> testList = new ArrayList<HashMap>();     HashMap<String, String> testMap1 = new HashMap<String, String>();     HashMap<String, String> testMap2 = new HashMap<String, String>();      testMap1.put('1_1', 'One');     testMap1.put('1_2', 'Two');     testMap1.put('1_3', 'Three');      testMap2.put('2_1', 'One');     testMap2.put('2_2', 'Two');     testMap2.put('2_3', 'Three');      testList.add(testMap1);     testList.add(testMap2);      System.out.println(jYaml.dump(testList));     System.out.println(snakeYaml.dump(testList)); 

The output from JYaml includes the serialised object’s class name whereas the output from SnakeYaml does not:

JYaml output:

- !java.util.HashMap   1_1: One   1_3: Three   1_2: Two - !java.util.HashMap   2_1: One   2_2: Two   2_3: Three 

SnakeYaml output:

- {'1_1': One, '1_3': Three, '1_2': Two} - {'2_1': One, '2_2': Two, '2_3': Three} 

I prefer the more ‘clean’ class name-less output of SnakeYaml as this would be more suitable for a language-neutral environment.

I prefer the speed of JYaml. Serialisation/deserialisation times increase linearly with the amount of data being processed, as opposed to exponentially with SnakeYaml.

I’d like to coerce JYaml into giving me class name-less output but am quite lost as to how this can be achieved.

Answer 1

Check the SnakeYAML latest source. It is now possible (same as in JYaml) to ignore implicit typing and always parse scalars as Strings. This is a few times faster. Look here and here to see how to use the new feature.

(With the RegularExpressions off serialisation/deserialisation times increase linearly with the amount of data being processed.)