How to check if element exists using a lambda expression?
The above answers require you to malloc a new stream object.
public <T>
boolean containsByLambda(Collection<? extends T> c, Predicate<? super T> p) {
for (final T z : c) {
if (p.test(z)) {
return true;
}
}
return false;
}
public boolean containsTabById(TabPane tabPane, String id) {
return containsByLambda(tabPane.getTabs(), z -> z.getId().equals(id));
}
...
if (containsTabById(tabPane, idToCheck))) {
...
}
Try to use anyMatch
of Lambda Expression. It is much better approach.
boolean idExists = tabPane.getTabs().stream()
.anyMatch(t -> t.getId().equals(idToCheck));
While the accepted answer is correct, I'll add a more elegant version (in my opinion):
boolean idExists = tabPane.getTabs().stream()
.map(Tab::getId)
.anyMatch(idToCheck::equals);
Don't neglect using Stream#map() which allows to flatten the data structure before applying the Predicate
.