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If this question fomes from a book, please tell us
full details of the book.
Tuan Dang wrote:. . . what type of object is byName . . . ?
DuckHelper$$Lambda$1/990368553
This is a λ. You are using a λ here to replace an anonymous class, as you would have used in Java7−. It is rarely necessary to find out its originating class, which you cannot find. Since the λ usually has local scope and doesn't even exist outwith the method it is declared in, all the information about it is in its code.
And where should i find the information about this type (or operation) in Java SE 8 Doc . . .
If the λ has local scope, or is a
private field, it would be impossible to write documentation comments and have them displayed. The
javadoc tool displays neither local variables nor
private members of a class, so there is no such thing as documentation to find.
You can find tutorials and books about λs however. If the λ uses
default methodss from Comparator, you can find their details under Comparator.