Sadly, Java 8 did not introduce pairs or tuples. You can always use org.apache.commons.lang3.tuple of course (which personally I do use in combination with Java 8) or you can create your own wrappers. Or use Maps. Or stuff like that, as is explained in the accepted answer to that question you linked to.
UPDATE: JDK 14 is introducing records as a preview feature. These aren't tuples, but can be used to save many of the same problems. In your specific example from above, that could look something like this:
public class Jdk14Example {
record CountForIndex(int index, long count) {}
public static void main(String[] args) {
boolean [][] directed_acyclic_graph = new boolean[][]{
{false, true, false, true, false, true},
{false, false, false, true, false, true},
{false, false, false, true, false, true},
{false, false, false, false, false, true},
{false, false, false, false, false, true},
{false, false, false, false, false, false}
};
System.out.println(
IntStream.range(0, directed_acyclic_graph.length)
.parallel()
.mapToObj(i -> {
long count = IntStream.range(0, directed_acyclic_graph[i].length)
.filter(j -> directed_acyclic_graph[j][i])
.count();
return new CountForIndex(i, count);
}
)
.filter(n -> n.count == 0)
.collect(() -> new ArrayList<CountForIndex>(), (c, e) -> c.add(e), (c1, c2) -> c1.addAll(c2))
);
}
}
When compiled and run with JDK 14 (at the time of writing, this an early access build) using the --enable-preview
flag, you get the following result:
[CountForIndex[index=0, count=0], CountForIndex[index=2, count=0], CountForIndex[index=4, count=0]]