[FIXED] Find duplicates in two lists List<int[]> using Streams

Issue

Find duplicates in two lists List<int[]> with streams

I have a list of int arrays. I need to find duplicates of these arrays using 2 lists of int arrays.

I did try to implement it, but I'm getting an empty array.

keys = [[1,1,0], [0,0,1], [1,2,1], [1,3,1], [1,3,2]];
phaseKey = [[1,3,2], [1,2,1], [0,0,2], [1,2,3], [1,0,3]];
desired result: [[[1,3,2]], [1,2,1]];

My code:

Stream.concat(Stream.of(keys.stream().flatMapToInt(Arrays::stream)),                     
        Stream.of(phaseKey.stream().flatMapToInt(Arrays::stream)))
                            .collect(Collectors.groupingBy(
                                    Function.identity(),
                                    Collectors.counting()))
                            .entrySet()
                            .stream()
                            .filter(m -> m.getValue() > 1)
                            .map(Map.Entry::getKey)
                            .toArray();

Solution

Given your two lists:

List<int[]> keys = // ....
List<int[]> phaseKey = //...

You just need to filter to find common arrays in both lists:

List<int[]> duplicates = keys.stream()
        .filter(k -> phaseKey.stream().anyMatch(p -> Arrays.equals(p,k)))
        .collect(Collectors.toList());

Answered By - Eritrean
Answer Checked By - Terry (JavaFixing Volunteer)