i have a string array like this:
firstArray = {"1", "2", "3", "4" };
and i have second array like this:
secondArray = {"2", "5", "6", "7" };
if i want to stream with one element, i can do like this:
firstArray.stream()
.filter(element -> !element.equals("2"))
.forEach((element) -> {
finalArrayList.add(element);
}
);
how can i stream first array with second arrays all elements in java 8 ?
If you want to keep only elements of the first array that you don't have in the second array using the Stream API, you could do it like this:
List<String> result = Arrays.stream(firstArray)
.filter(el -> Arrays.stream(secondArray).noneMatch(el::equals))
.collect(Collectors.toList());
What exactly do you want to do? Get all the elements in the first array that are also present in the second array?
Like this:
String[] firstArray = {"1", "2", "3", "4"};
String[] secondArray = {"2", "5", "6", "7"};
List<String> finalArrayList = Arrays.stream(firstArray)
.filter(element -> arrayContains(secondArray, element))
.collect(Collectors.toList());
Using the following utility method:
public static <T> boolean arrayContains(T[] array, T element) {
return Arrays.stream(array)
.filter(e -> e.equals(element))
.findFirst().isPresent();
}
Note: Instead of using forEach and adding the results to finalArrayList, use a collector. That's more pure, from a functional programming point of view.
edit - With Holger's tips (see his comment below):
public static <T> boolean arrayContains(T[] array, T element) {
return Arrays.stream(array)
.anyMatch(e -> e.equals(element));
}
anyMatch(predicate) which is to prefer over filter(predicate).findFirst().isPresent(). Besides, if you are only interested in the presence of a match, findAny() would be more appropriate than findFirst()…
Stream.concat(Stream, Stream)docs.oracle.com/javase/8/docs/api/java/util/stream/…