Sunflame :
I have a class Model with the following signature:
class Model {
private String stringA;
private String stringB;
public Model(String stringA, String stringB) {
this.stringA = stringA;
this.stringB = stringB;
}
public String getStringA() {
return stringA;
}
public String getStringB() {
return stringB;
}
}
I would like to map a List<Model> to a List<String> containing both stringA and stringB in a single stream
List<String> strings = models.stream()
.mapFirst(Model::getStringA)
.thenMap(Model::getStringB)
.collect(Collectors.toList());
or:
List<String> strings = models.stream()
.map(Mapping.and(Model::getStringA,Model::getStringB))
.collect(Collectors.toList());
Of course none of them compiles, but you get the idea.
Is it somehow possible?
Edit:
Example:
Model ab = new Model("A","B");
Model cd = new Model("C","D");
List<String> stringsFromModels = {"A","B","C","D"};
Ousmane D. :
You can have a list of all the values one after another like so:
List<String> resultSet =
modelList.stream()
.flatMap(e -> Stream.of(e.getStringA(), e.getStringB()))
.collect(Collectors.toList());
The function passed to flatMap will be applied to each element yielding a Stream<String>. The use of flatMap is necessary here to collapse all the nested Stream<Stream<String>> to a Stream<String> and therefore enabling us to collect the elements into a List<String>.
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