MalformedJsonException: Invalid escape sequence

Question

I have a json string as below:

{"person":[{"initials":"C. P.","familyName":"Mangum"}],"title":"Blood and tissue oxygen carriers","text":"(ed). \992d. Springer-Verlag, Heidelberg"}

When de-serializing above json string using gson as below:

gson.fromJson(json, MyObject.class)

I see MalformedJsonException exception.

Caused by: com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Invalid escape sequence at line 1 column 115 path $.test

Then I tried setting JsonReader setLenient to true

JsonReader reader = new JsonReader(new StringReader(row));
reader.setLenient(true);
gson.fromJson(reader, MyObject.class);

But now I get ClassCastException now:

Caused by: java.lang.ClassCastException: class MyObject cannot be cast to class com.google.gson.JsonElement (MyObject and com.google.gson.JsonElement are in unnamed module of loader 'app')

Later I tried using setLenient() in GsonBuilder, but it failed with original MalformedJsonException exception

Gson gson = new GsonBuilder().setLenient().create();
gson.fromJson(row, MyObject.class);

I am not sure if I can use theString = theString.replace("\\", "\\\\"); is safe. Is there good practice to be followed?

Can I please know how I can process escaped characters as above?

Answer 1

json is malformed, it should have a double \ for \\992d in the original form:

{
    "person": [{
        "initials": "C. P.",
        "familyName": "Mangum"
    }],
    "title": "Blood and tissue oxygen carriers",
    "text": "(ed). \\992d. Springer-Verlag, Heidelberg"
}

Answer 2

You need to escape your "text" element as below, then it will be a valid json.

{
    "person": [{
        "initials": "C. P.",
        "familyName": "Mangum"
    }],
    "title": "Blood and tissue oxygen carriers",
    "text": "(ed). \\992d. Springer-Verlag, Heidelberg"
}

Apache Commons

If you're already using Apache commons, it provides a static method for this:

StringEscapeUtils.escapeJson("some string")

It converts any string into one that's properly escaped for inclusion in JSON.

https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/StringEscapeUtils.html