Issue with optional usage (java 8)

Question

I am trying to use stream with my code below. My problem is my return value. This piece of code return an Optional not a boolean:

ogps.stream().filter(elt -> (elt.getLineNumbers() != null && !vg.getLineNumbers().isEmpty())).findFirst();

Can you please guide me? Thks

//The original code
public static boolean isOrderOk(List<OrderGroup> ogps) {
        if (ogps == null || ogps.isEmpty()) {
            return true;
        }
        for (OrderGroup elt : ogps) {
            if (elt.getLineNumbers() != null && !vg.getLineNumbers().isEmpty()) {
                return false;
            }
        }
        return true;
}

//The new code with stream usage
public static boolean isOrderOk(List<OrderGroup> ogps) {
        if (ogps == null || ogps.isEmpty()) {
            return true;
        }
        return ogps.stream()
                .filter(elt -> (elt.getLineNumbers() != null && !vg.getLineNumbers().isEmpty()))
                .findFirst();
        return true;
}

See anyMatch. It is a short-circuit terminal operation made exactly for this purpose. — M. Prokhorov
– M. Prokhorov, Commented Apr 28, 2017 at 12:55
And if you need the value from the Optional use it's get method — Robin Topper
– Robin Topper, Commented Apr 28, 2017 at 12:55

assylias · Accepted Answer · 2017-04-28 12:55:47Z

1

You are probably looking for something like:

public static boolean isOrderOk(List<OrderGroup> ogps) {
    if (ogps == null || ogps.isEmpty()) {
        return true;
    }
    return ! ogps.stream()
        .anyMatch(elt -> (elt.getLineNumbers() != null && !vg.getLineNumbers().isEmpty()));
}

answered Apr 28, 2017 at 12:55

assylias

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Comments

delca85 · Accepted Answer · 2017-04-28 12:56:15Z

0

The reason is that you are using findFirst method of stream class and it returns Optional type as you can see here.

answered Apr 28, 2017 at 12:56

delca85

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