CODEWITHSUNDEEP
javalambda
mrs
mrs

Reputation: 217

method ref from lambda

In one of the method we used lambda expression (below) nesting streams.

return req.gUs().stream()
.map((**cfg) -> {
.filter(Optional::isPresent)
.map(Optional::get);

I want to move part of the code using some helper methods and method reference (below).

(cfg) -> {
return rsp.getUs().stream()
.filter(result.getId())    
.map((result) -> gEvent(index, Builder, cfg));

Any suggestions are greatly appreciated.

Upvotes: 1

Views: 121

Answers (1)

Matthias Danetzky
Matthias Danetzky

Reputation: 682

You can make a method, that returns a Function:

return req.getUs().stream()
.map(myFunction(rsp, index, headerBuilder))
.flatMap(stream -> stream)
.filter(Optional::isPresent)
.map(Optional::get);

private Function<CFGType, GenerateReturnType> myFunction(RspType rsp, IndexType index, HeaderType header){
  return (cfg) -> {
    return rsp.getPerUs().stream()
    .filter((result) -> cfg.getId() == result.getId())
    .filter((result) -> result.getCode() == ResultCode.SUCCESS)
    .map((result) -> generateEvent(index, headerBuilder, cfg));
  }
}

Or you could use a method reference if the rsp, index and header are fields:

return req.getUs().stream()
.map(this::myFunction)
.flatMap(stream -> stream)
.filter(Optional::isPresent)
.map(Optional::get);

private GenerateType myFunction(CFGType cfg) {
  return rsp.getUs().stream()
  .filter((result) -> cfg.getUsChId() == result.getChId())
  .filter((result) -> result.getResultCode() == ResultCode.SUCCESS)
  .map((result) -> generateEvent(index, headerBuilder, cfg));
}

Upvotes: 1

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