DFLib, a Java DataFrame

DFLib is a lightweight, pure Java implementation of a DataFrame data structure. It provides data manipulation capabilities similar to SQL - filtering, joins, unions, and more - only done as step-by-step in-memory transformations that are easy to compose and understand. DFLib includes connectors for CSV, Excel, RDBMS, Avro, Parquet, JSON, and can be easily adapted to other formats. It is open source and distributed under the Apache License.

To get started, follow the documentation