java - 以不同的顺序比较两个具有相同键的json对象

Question

Given two json objects

String a1 = "{\"a\":[{\"b\":\"1\"}, {\"b\":\"2\"}]}";
String a2 = "{\"a\":[{\"b\":\"2\"}, {\"b\":\"1\"}]}";

I'd like to compare them regardless of the order of objects in the array. I'm using Jackson but it doesn't work.

ObjectMapper om = new ObjectMapper().configure(
    SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true
);
Map<String, Object> m1 = (Map<String, Object>)(om.readValue(a1, Map.class));
Map<String, Object> m2 = (Map<String, Object>)(om.readValue(a2, Map.class));
System.out.println(m1.equals(m2));

Is there any handy way to compare them properly?

Answer 1

Your om.readValue() call is returning a Map<String, List<Map<String, Integer>>> :

Map<String, List<Map<String, Integer>>> m1 = om.readValue(a1, Map.class);
Map<String, List<Map<String, Integer>>> m2 = om.readValue(a2, Map.class);

System.out.println(m1); //{a=[{b=1}, {b=2}]}
System.out.println(m2); //{a=[{b=2}, {b=1}]}

The lists {b=1}, {b=2} and {b=2}, {b=1} are not equal because of their order. So I converted the list to a HashSet and then ran the comparison:

Map<String, HashSet<Map<String, Integer>>> m1Collected = m1.entrySet().stream()
        .map(e -> Map.entry(e.getKey(), new HashSet<>(e.getValue())))
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

Map<String, HashSet<Map<String, Integer>>> m2Collected = m2.entrySet().stream()
        .map(e -> Map.entry(e.getKey(), new HashSet<>(e.getValue())))
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

System.out.println(m1Collected.equals(m2Collected)); //prints true

You can also use JSONassert with strict mode set to false, to compare JSONs ignoring the order.