Java Utililty Methods Stream Operation

List of utility methods to do Stream Operation

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Description

The list of methods to do Stream Operation are organized into topic(s).

Method

StreamfindStreamAmongst(Class clazz, Collection instances)
find Stream Amongst 
return instances.stream().filter(clazz::isInstance).map(clazz::cast);
TfirstValue(Stream stream)
first Value 
return stream.findAny().get();
StreamflatOptionals(Stream> list)
flat Optionals 
return list.filter(Optional::isPresent).map(opt -> opt.get());
Map>flattenFeatureStreamToMap( Stream>>> stream)
Convert a flatten nested stream(feature family, stream(feature name. 
Map<String, Map<String, Double>> outputFeatureMap = new HashMap<>();
stream.forEach(inputFamilyEntry -> {
    String familyName = inputFamilyEntry.getKey();
    Map<String, Double> outputFeatureFamily = outputFeatureMap.get(familyName);
    if (outputFeatureFamily == null) {
        outputFeatureFamily = new HashMap<>();
        outputFeatureMap.put(familyName, outputFeatureFamily);
    final Map<String, Double> finalFeatures = outputFeatureFamily;
    inputFamilyEntry.getValue().forEach(feature -> finalFeatures.put(feature.getKey(), feature.getValue()));
});
return outputFeatureMap;
intgcd(IntStream numbers)
Calculate the greatest commom divisor of all numbers in the int stream 
return numbers.reduce(0, (x, y) -> gcd(x, y));
IntStreamgetOSIllegalCharacterStream(String path)
get OS Illegal Character Stream 
return path.chars().filter(c -> c < '\u0020' || WINDOWS_RESERVED_CHARS.indexOf(c) != -1
        || reserverdCharacters.indexOf(c) != -1);
StreamgetStream(Iterable iterable)
Get a sequential Stream from an Iterable . 
return StreamSupport.stream(iterable.spliterator(), false);
StreamgetStringStreamFromArray(String... ids)
Returns a stream of strings from a string array 
return Stream.of(ids);
LongStreaminfiniteParallelStream()
Creates an infinite parallel long stream. 
return iterate(1L, l -> l + 1).parallel();
Streaminterleave(Stream a, Stream b)
interleave 
List<T9> ar = a.collect(Collectors.toList());
List<T9> br = b.collect(Collectors.toList());
ArrayList<T9> r = new ArrayList<>(ar.size() + br.size());
for (int i = 0; i < Math.max(ar.size(), br.size()); i++) {
    if (i < ar.size())
        r.add(ar.get(i));
    if (i < br.size())
        r.add(br.get(i));
...