Java 集合的 Optional 工具类

模仿java.util.Optional写的工具类，用于集合的判空以及后续处理

public class CollectOptional {

    private static final CollectOptional EMPTY = new CollectOptional<>();

    private final Collection collect;


    private CollectOptional() {
        this.collect = null;
    }

    private CollectOptional(Collection collect) {
        this.collect = collect;
    }


    public static  CollectOptional empty() {
        @SuppressWarnings("unchecked")
        CollectOptional collect = (CollectOptional) EMPTY;
        return collect;
    }

    
    public static  CollectOptional ofEmpty(Collection collect) {
        if(CollectionUtils.isEmpty(collect)){
            return empty();
        }
        return new CollectOptional<>(collect);
    }

    
    public Collection get(){
        if (collect == null) {
            throw new NoSuchElementException("No value present");
        }
        return collect;
    }

    
    public boolean isNotEmpty() {
        return !CollectionUtils.isEmpty(collect);
    }

    
    public CollectOptional isEmpty(Consumer> consumer) {
         if(CollectionUtils.isEmpty(collect)){
             consumer.accept(collect);
         }
         return this;
    }

    
    public void ifNotEmpty(Consumer> consumer) {
        if(CollectionUtils.isEmpty(collect)){
            return;
        }
        consumer.accept(collect);
    }

    
    public  R ifPresentApply(Function, R> function) {
        if(CollectionUtils.isEmpty(collect)){
            return null;
        }
        return function.apply(collect);
    }

}