I defined my own predicate:
public interface StringPredicate extends Predicate<String> {
It works, but if I write:
myPred.and( strEl -> strEl != null);
the result is a Predicate<String> not a StringPredicate. How can I define a combine operation as well?
You can define your own and method in your StringPredicate interface:
public interface StringPredicate extends Predicate<String> {
default StringPredicate and(StringPredicate other) {
Objects.requireNonNull(other);
return (t) -> test(t) && other.test(t);
}
}
Now, the following will work:
StringPredicate myPred = s -> s.length() > 0;
StringPredicate combined = myPred.and(strEl -> strEl.length () < 5);