get a list of unique date from the stream grouping

I have data:

id|date
1 |12-12-2021
2 |12-12-2021
3 |13-12-2021

Want to get a list of dates: [“12-12-2021”, “13-12-2021”]

Using stream, I can get a map:

txs.stream().collect(Collectors.groupingBy(g -> g.getDate()));

I would like to convert to list in from the stream above.

Answer

groupingBy is not the best choice in your case. Use distinct instead. It will automatically filter out all duplicates.

txs.stream().map(g -> g.getDate()).distinct().collect(Collectors.toList());