[NETBEANS-3755] "Can use functional operations" hint creates uncompilable code with nested loops (Unexpected return value)

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 11.2
• Component/s: java - Hints

Environment

OpenJDK 13+33

• Assignee: Unassigned
• Reporter: dennis lucero
• Created: 27/Jan/20 18:19
• Updated: 27/Jan/20 18:19

Description

Consider this code:

private static boolean deepContains(
        final String needle,
        final Collection<Collection<String>> haystack) {
    for (final Collection<String> hay : haystack) {
        for (final String check : hay) {
            if (check.equals(needle)) {
                return true;
            }
        }
    }
    return false;
}

NetBeans suggests to replace the outer loop with with a functional operation, resulting in

private static boolean deepContains(
        final String needle,
        final Collection<Collection<String>> haystack) {
    haystack.forEach((hay) -> {
        for (final String check : hay) {
            if (check.equals(needle)) {
                return true;
            }
        }
    });
    return false;
}

This does not compile. Error messages:
For the outer loop:

incompatible types: unexpected return value

For the inner loop:
 

for-each not applicable to expression type
required: array or java.lang.Iterable
found: T
where T is a type-variable:
T extends Object declared in interface Iterable