import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.function.Function; import java.util.stream.Collector; import java.util.stream.Collectors; class Test { static class A { static class Row { public String get(int index) { return "test"; } } void foo(List<Row> list) { list.stream().collect(Collectors.toMap(a -> String.valueOf(a.ge<caret>t(0)), a -> String.valueOf(a.get(1)))); } } }