Jackson JSON Not Formatting Correctly - json

Question

I have data that looks like this:
{
"status": "success",
"data": {
"irrelevant": {
"serialNumber": "XYZ",
"version": "4.6"
},
"data": {
"lib": {
"files": [
"data1",
"data2",
"data3",
"data4"
],
"another file": [
"file.jar",
"lib.jar"
],
"dirs": []
},
"jvm": {
"maxHeap": 10,
"maxPermSize": "12"
},
"serverId": "134",
"version": "2.3"
}
}
}
Here is the function I'm using to prettify the JSON data:
public static String stringify(Object o, int space) {
ObjectMapper mapper = new ObjectMapper();
try {
return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(o);
} catch (Exception e) {
return null;
}
}
I am using the Jackson JSON Processor to format JSON data into a String.
For some reason the JSON format is not in the format that I need. When passing the data to that function, the format I'm getting is this:
{
"status": "success",
"data": {
"irrelevant": {
"serialNumber": "XYZ",
"version": "4.6"
},
"another data": {
"lib": {
"files": [ "data1", "data2", "data3", "data4" ],
"another file": [ "file.jar", "lib.jar" ],
"dirs": []
},
"jvm": {
"maxHeap": 10,
"maxPermSize": "12"
},
"serverId": "134",
"version": "2.3"
}
}
}
As you can see under the "another data" object, the arrays are displayed as one whole line instead of a new line for each item in the array. I'm not sure how to modify my stringify function for it to format the JSON data correctly.

Answer 1

You should check how DefaultPrettyPrinter looks like. Really interesting in this class is the _arrayIndenter property. The default value for this property is FixedSpaceIndenter class. You should change it with Lf2SpacesIndenter class.
Your method should looks like this:
public static String stringify(Object o) {
try {
ObjectMapper mapper = new ObjectMapper();
DefaultPrettyPrinter printer = new DefaultPrettyPrinter();
printer.indentArraysWith(new Lf2SpacesIndenter());
return mapper.writer(printer).writeValueAsString(o);
} catch (Exception e) {
return null;
}
}

Answer 2

I don't have enough reputation to add the comment, but referring to the above answer Lf2SpacesIndenter is removed from the newer Jackson's API (2.7 and up), so instead use:
printer.indentArraysWith(DefaultIndenter.SYSTEM_LINEFEED_INSTANCE);
Source of the solution