Java 8 forEach with index

Question

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  - gt  query bind idx  e      The best I could do right now is   int idx   0  params forEach e - gt      query bind idx  e     idx

User · Answer

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  lt  params size    idx    query bind idx  params get idx

User · Answer

It works with params if you capture an array with one element  that holds the current index   int   idx     0    params forEach e - gt  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 - gt  query bind idx 0     e

User · Answer

Since you are iterating over an indexable collection  lists  etc    I presume that you can then just iterate with the indices of the elements   IntStream range 0  params size       forEach idx - gt      query bind        idx        params get idx                The resulting code is similar to iterating a list with the classic i  -style for loop  except with easier parallelizability  assuming  of course  that concurrent read-only access to params is safe

[java] Java 8 forEach with index

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