Parse a JSON file in Java
The initial value of a map variable is not used, you can avoid this assignment and inline the variable. o is not used too.

If indexes in a map is consequent then it is better to use a List instead of Map. So the part of the code can be rewritten following way:

List&lt;Map&lt;String, String&gt;&gt; jsonmaps = new ArrayList&lt;&gt;();
for (Object j : jsons) {
    jsonmaps.add(mapper.readValue(j.toString(),
        new TypeReference&lt;Map&lt;String, String&gt;&gt;() {}));
}