Java Parallel Stream AnyMatch of Parallel Stream's one field

Question

I am novice in Java, but I would like to use Parallel Streams instead For statement. So I have an ArrayList of pojo object like bellow and try check field of one object with second object:

List<DataOne> dol = new ArrayList<>();
/// dol.add(new DataOne("fieldA", "fieldB", "fieldC")); ...

List<DataTwo> dtl = new ArrayList<>();
/// dol.add(new DataTwo("field1", "field2", "field3")); ...

boolean cc = dol.parallelStream()
    .filter(Objects::nonNull)
    .filter(a ->  a.getFieldA() != null && a.getFieldB() != null && a.getFieldC() != null)
    .anyMatch(a -> 
         dtl.parallelStream()
         .filter(Objects::notNull)
         .filter(b -> b.getField1 != null && b.getField2 != null && b.getField3 != null)
         .anyMatch(b -> b.getField1.contains(a.getFieldA)));

But it is not working... What I did wrong?

Answer 1

You are using contains() method to find the matching fields. DataTwo.getField1().contains(DataOne.getFieldA()) ---> "field1".contains("fieldA") --> returns "false" since "field1" does not contain any "fieldA". But if DataTwo.field1 was something like "fieldAekstra" then DataTwo.getField1().contains(DataOne.getFieldA()) --> would return true because "fieldAekstra" contains one "fieldA".

Example below is running correctly and outputs "Match Found". I just corrected some typos. Overall your code is working, it is just that there were no matching strings in your example list items.

List<DataOne> dol = new ArrayList<>();
     dol.add(new DataOne("fieldA", "fieldB", "fieldC")); 
     dol.add(new DataOne("fieldD", "fieldF", "fieldH"));
     dol.add(new DataOne("fieldK", "fieldM", "fieldN"));
    List<DataTwo> dtl = new ArrayList<>();
    dtl.add(new DataTwo("fieldAEkstra", "fieldBEkstra", "fieldCEkstra")); 
    dtl.add(new DataTwo("fieldDEkstra", "fieldFEkstra", "fieldHEkstra"));
    dtl.add(new DataTwo("fieldTEkstra", "fieldOEkstra", "fieldWEkstra"));
    /*dtl.add(new DataTwo("field1", "field2", "field3")); 
    dtl.add(new DataTwo("field4", "field5", "field6")); 
    dtl.add(new DataTwo("field7", "field8", "field9")); */
    boolean cc = dol.parallelStream()
            .filter(Objects::nonNull)
            .filter(a ->  a.getFieldA() != null && a.getFieldB() != null && a.getFieldC() != null)
            .anyMatch(a -> 
                 dtl.parallelStream()
                 .filter(Objects::nonNull)
                 .filter(b -> b.getField1() != null && b.getField2() != null && b.getField3() != null)
                 .anyMatch(b -> b.getField1().contains(a.getFieldA())));
    if(cc)
        System.out.println("Match found!");
    else
        System.out.println("No Match !");

Output:

Match found!