Dataset<Row> words = df
            .selectExpr("CAST (value AS STRING)")
            .as(Encoders.STRING())
            .withColumn("id", split(col("value"), ",").getItem(0))
            .withColumn("country", split(col("value"), ",").getItem(1))
            .withColumn("timestamp", split(col("value"), ",").getItem(2));


+----+---------+----------+
|id  |country  |timestamp |
+----+---------+----------+
|2922|de       |1231231232|
|4195|de       |1231232424|
|6796|fr       |1232412323|
+----+---------+----------+

Dataset<String> words.map(row -> {
    //do something with every entry of each row e.g.
            Person person = new Person(id, country, timestamp);
            String name = person.getName();
            return name;
    };