How to generate HBase java Put class from String Array?

Question

I am newbie on Java 8 lambda and stream programming. This is simple source which generate HBase Put class from String array.

List<String> list = new ArrayList<>(5);
list.add("1," + "colFamily" + ",a,1");
list.add("2," + "colFamily" + ",a,2");
list.add("3," + "colFamily" + ",a,3");
list.add("4," + "colFamily" + ",a,4");
list.add("5," + "colFamily" + ",a,5");

for (int i=0 ; i<list.size() ; i++) {
  String[] cells = list.get(i).split(",");

  Put put = new Put(Bytes.toBytes(cells[0]));
  put.addColumn(Bytes.toBytes(cells[1]),Bytes.toBytes(cells[2]),Bytes.toBytes(cells[3]));

System.out.println(put);

Results are generated correctly like below,

{"totalColumns":1,"row":"1","families":{"colFamily":[{"qualifier":"a","vlen":1,"tag":[],"timestamp":9223372036854775807}]}}
{"totalColumns":1,"row":"2","families":{"colFamily":[{"qualifier":"a","vlen":1,"tag":[],"timestamp":9223372036854775807}]}}
{"totalColumns":1,"row":"3","families":{"colFamily":[{"qualifier":"a","vlen":1,"tag":[],"timestamp":9223372036854775807}]}}
{"totalColumns":1,"row":"4","families":{"colFamily":[{"qualifier":"a","vlen":1,"tag":[],"timestamp":9223372036854775807}]}}
{"totalColumns":1,"row":"5","families":{"colFamily":[{"qualifier":"a","vlen":1,"tag":[],"timestamp":9223372036854775807}]}}

But by using Java 8 stream, I failed to generate the same results, below is the codes.

System.out.println(list.stream().collect(Collectors.mapping(l -> new Put(Bytes.toBytes(l)), Collectors.toList())));

But definitely the above code brings the wrong results.

[{"totalColumns":0,"row":"1,colFamily,a,1","families":{}}, {"totalColumns":0,"row":"2,colFamily,a,2","families":{}}, {"totalColumns":0,"row":"3,colFamily,a,3","families":{}}, {"totalColumns":0,"row":"4,colFamily,a,4","families":{}}, {"totalColumns":0,"row":"5,colFamily,a,5","families":{}}]

I have no idea how to split comma-seperated-Strings to String array using java 8 stream function.

Answer 1

How about this:

list
.stream()
.map(s -> s.split(","))
.map(cells -> {
    Put put = new Put(Bytes.toBytes(cells[0]));
    put.addColumn(Bytes.toBytes(cells[1]), Bytes.toBytes(cells[2]), Bytes.toBytes(cells[3]));
    return put;
})
.forEach(System.out::println) // or .collect to list