Is there a way to build a forEach
method in Java 8 that iterates with an index? Ideally I'd like something like this:
params.forEach((idx, e) -> query.bind(idx, e));
The best I could do right now is:
int idx = 0;
params.forEach(e -> {
query.bind(idx, e);
idx++;
});
It works with params if you capture an array with one element, that holds the current index.
int[] idx = { 0 };
params.forEach(e -> query.bind(idx[0]++, e));
The above code assumes, that the method forEach iterates through the elements in encounter order. The interface Iterable specifies this behaviour for all classes unless otherwise documented. Apparently it works for all implementations of Iterable from the standard library, and changing this behaviour in the future would break backward-compatibility.
If you are working with Streams instead of Collections/Iterables, you should use forEachOrdered, because forEach can be executed concurrently and the elements can occur in different order. The following code works for both sequential and parallel streams:
int[] idx = { 0 };
params.stream().forEachOrdered(e -> query.bind(idx[0]++, e));
There are workarounds but no clean/short/sweet way to do it with streams and to be honest, you would probably be better off with:
int idx = 0;
for (Param p : params) query.bind(idx++, p);
Or the older style:
for (int idx = 0; idx < params.size(); idx++) query.bind(idx, params.get(idx));
Source: Stackoverflow.com