Methods to check form validity and to count invalid form fields

Question

I have two these methods. Their loops are pretty similar. I'd like to refactor it to avoid duplicate nested loops. How could I do that?

@Override
public boolean isValid() {
 for (final FormSection formSection : getFormSections()) {
 for (final Component fieldComponent : formSection) {
 boolean isFieldValid = ((Field)fieldComponent).isValid();
 if(!isFieldValid){
 return false;
 }
 }
 }
 return true;
}
private int countErrors() {
 int errorAmount = 0;
 for (final FormSection formSection : getFormSections()) {
 for (final Component fieldComponent : formSection) {
 boolean isFieldValid = ((Field)fieldComponent).isValid();
 if(!isFieldValid){
 errorAmount++;
 }
 }
 }
 return errorAmount;
}

I've tried to use interface but it doesn't look good.

interface FieldHandler {
 boolean process(AtomicInteger number);
}
@Override
public boolean isValid() {
 return handleTextFieldsInTabs(new FieldHandler() {
 @Override
 public boolean process(AtomicInteger number) {
 return false;
 }
 }, null);
}
boolean handleTextFieldsInTabs(FieldHandler fieldHandler, AtomicInteger number) {
 for (final FormSection formSection : getFormSections()) {
 for (final Component fieldComponent : formSection) {
 boolean isFieldValid = ((Field)fieldComponent).isValid();
 if(!isFieldValid && !fieldHandler.process(number)) {
 return false;
 }
 }
 }
 return true;
}
private int countErrors() {
 final AtomicInteger errorAmount = new AtomicInteger(0);
 handleTextFieldsInTabs(new FieldHandler() {
 @Override
 public boolean process(AtomicInteger number) {
 number.incrementAndGet();
 return true;
 }
 }, errorAmount);
 return errorAmount.intValue();
}

• h.j.k.: Are you on Java 8?
• emeraldhieu: Users can use Java 7 to run the code. That's why I need a non-lambda way.
• Genzer: Do you have any 3rd party library like Apache's common-collections4 or Google's guava?

Answer 1

If you are using Google's guava, I would suggest:

@Override
public boolean isValid() {
 // Firstly, flat your Iterable<Iterable<Component>> getFormSections()
 // into Iterable<Component>.
 // Then we use a Predicate to check whether there is any match.
 return Iterables.all(
 Iterables.concat(getFormSections()), validComponents()); 
}
@Override
public int countErrors() {
 return Iterables.size(
 Iterables.filter(Iterables.concat(getFormSections()), Predicates.not(validComponents()));
}
// - Positive names is always preferable
// - This method is static simply because it does not access to any instance varibles. It is easier to extract it out into another class.
private static Predicate<Component> validComponent() {
 new Predicate<Component>() {
 @Override
 public boolean apply(Component input) {
 return // your logic here
 }
 };
}