CODEWITHSUNDEEP
javajsonjackson
Alex Man
Alex Man

Reputation: 4886

Convert Java String to HashMap Object

I have created an application for converting the HashMap object to String, its working fine, The problem which i am facing is that i want to convert the HashMap string again back to HasMap object, when i tried that by using the following code , I am getting exception as shown below

Unexpected character ('u' (code 117)): was expecting double-quote to start field name

Can anyone please tell me some solution for this

My code is given below

Map<String,Object> map = new HashMap<String,Object>();
map.put("userVisible", true);
map.put("userId", "1256");

ObjectMapper mapper = new ObjectMapper();
try {
    map =  mapper.readValue(map.toString(), new TypeReference<HashMap<String,Object>>(){});
    System.out.println(map.get("userId"));
} catch (Exception e) {
    e.printStackTrace();
}

Update 1

As suggested by @chrylis I have used Feature.ALLOW_UNQUOTED_FIELD_NAMES like as shown below, but now i am getting the following exception

Unexpected character ('=' (code 61)): was expecting a colon to separate field name and value

Updated Code

Map<String,Object> map = new HashMap<String,Object>();
map.put("userVisible", true);
map.put("userId", "1256");
ObjectMapper mapper = new ObjectMapper();
mapper.configure(Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
try {
    map =  mapper.readValue(map.toString(), new TypeReference<HashMap<String,Object>>(){});
    System.out.println(map.get("userId"));
} catch (Exception e) {
    e.printStackTrace();
}

Upvotes: 0

Views: 4370

Answers (1)

chrylis -cautiouslyoptimistic-
chrylis -cautiouslyoptimistic-

Reputation: 77187

You're getting this error because JSON specifies that you have to put field names in quotation marks, unlike in a regular JavaScript object. You can tell Jackson to permit unquoted field names by configuring the ObjectMapper so:

mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);

Update

It appears that a more fundamental problem is that you're trying to use Java toString() to convert the map to a String, and a Jackson JSON mapper to convert it back. The two are completely different formats, and if you need to be able to convert the string back into an object, you should probably use the Jackson mapper to turn the map into JSON in the first place.

Upvotes: 2

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