Guava Spliter is returning me a Collection but I want a HashMap

Question

I'm trying to convert a JSON string (returned on a HTTP Response by a web service) to a HashMap. In Python, I could've simply used json.loads(string_response) and it would've given me a nice dictionary. I'm trying to find a similar thing in Java.

My snippet is-

String result = "{\"packetsReceived_Audio\":\"\",\"packetsReceived_Screen\":\"\",\"packetsReceived_Video\":\"\",\"packetsSent_Audio\":\"\",\"packetsSent_Screen\":\"\",\"packetsSent_Video\":\"\",\"sequenceNumber\":\"0\"}";
Map map = Splitter.on(",").withKeyValueSeparator(":").split(result);

As one of the comments below point out that it should already return a hash map, it really isn't. Its returning me a collection with each item containing sub items - "key" and "value". See attached image for clarity. What I'm expecting is a HashMap.

I know I can add another step to create a usual Map but I wanted to check if there's something available in the framework already.

Thanks!

The Javadoc suggests you should already be getting a Map from that line alone. — Louis Wasserman, Apr 17 '19 at 02:44
@LouisWassermanYes, I would also think so but its returning something like a collection (see the attached image above) — Sankalp, Apr 17 '19 at 04:33
In Python you use a JSON parser. In Java you want to parse it yourself. Maybe pull in a JSON parsing lib. https://www.baeldung.com/java-org-json — Lesiak, Apr 17 '19 at 05:44
`Collections$UnmodifiableMap` is a type of `Map`, not a `Collection`. If you expect a `HashMap` specifically, just pass it to the copy constructor. — shmosel, Apr 17 '19 at 06:52
Yup. That debugging information tells us that you _have_ a perfectly valid Map. Not a HashMap, but a valid map. — Louis Wasserman, Apr 17 '19 at 17:04
Note that is an awful way to parse JSON. Use a proper parser instead trying to split it by hand. — shmosel, Apr 23 '19 at 09:03

Apokralipsa · Answer 1 · 2019-04-18T05:04:55.907

Splitter does return a map after you callwithKeyValueSeparator. Look at the greyed out text in {}'s which says what is the type of the map variable. It's an unmodifiable map which implements the map. You see the entry set too because your IDE introspects the internal implementation of the unmodifiable map.

Either way I think you would be better off using a library specifically built for parsing json. It would handle corner cases like json values containing colons. Here are some examples in Jackson.

Guava Spliter is returning me a Collection but I want a HashMap

1 Answers1