Converting an CSV file to a JSON object in Java

Question

Is there an open source java library to convert a CSV (or XLS) file to a JSON object?

I tried using json.cdl, but somehow it does not seem to work for large CSV stri

Answer 1

With Java 8, writing JSON is at hand.

You didn't specify what JSON API you want, so I assume by "JSON object" you mean a string with a serialized JSON object.

What I did in the CSV Cruncher project:

1. Load the CSV using HSQLDB. That's a relatively small (~2 MB) library, which actually implements a SQL 2008 database.
2. Query that database using JDBC.
3. Build a JDK JSON object (javax.json.JsonObject) and serialize it.

Here's how to do it:

static void convertResultToJson(ResultSet resultSet, Path destFile, boolean printAsArray) 
{
            OutputStream outS = new BufferedOutputStream(new FileOutputStream(destFile.toFile()));
            Writer outW = new OutputStreamWriter(outS, StandardCharsets.UTF_8);

            // javax.json way
            JsonObjectBuilder builder = Json.createObjectBuilder();
            // Columns
            for (int colIndex = 1; colIndex <= metaData.getColumnCount(); colIndex++) {
                addTheRightTypeToJavaxJsonBuilder(resultSet, colIndex, builder);
            }
            JsonObject jsonObject = builder.build();
            JsonWriter writer = Json.createWriter(outW);
            writer.writeObject(jsonObject);

The whole impl is here. (Originally I wrote my own CSV parsing and JSON writing, but figured out both are complicated enough to reach for a tested out-of-the-shelf library.)