tablestreams is a tool for streaming tables in and out of a program. The interface is generic across multiple table formats, and so can also be used to convert between them. Currently supported are TSV, CSV, DSV (CSV with delimiters other than commas), and (buggy) XLSX.

Here, a table is read from the TSV format to a CSV format:

TableReader reader = new TSVTableReader(new FileInputStream("table.tsv"));
TableWriter writer = new CSVTableWriter(new FileOutputStream("table.csv"));
writer.writeTable(reader);

This does the same except that it only reads/writes one line:

TableReader reader = new TSVTableReader(new FileInputStream("table.tsv"));
TableWriter writer = new CSVTableWriter(new FileOutputStream("table.csv"));
writer.writeRow(reader.readRow());

I have tried to write my own XLSX parser, but it is hard to know how often it will work, as documentation of the format online is a bit lacking. However, the library can both read and write XLSX files.