private Collection convertCollection()

in dubbo-rpc/dubbo-rpc-triple/src/main/java/org/apache/dubbo/rpc/protocol/tri/rest/argument/GeneralTypeConverter.java [858:931]
74 lines of code
25 McCabe index (conditional complexity)

    private Collection convertCollection(Collection source, Class targetClass) {
        if (targetClass.isInstance(source)) {
            return source;
        }
        if (targetClass.isInterface()) {
            if (targetClass == List.class || targetClass == Collection.class) {
                return new ArrayList<>(source);
            }
            if (targetClass == Set.class) {
                return new HashSet<>(source);
            }
            if (targetClass == SortedSet.class) {
                return new LinkedHashSet(source);
            }
            if (targetClass == Queue.class || targetClass == Deque.class) {
                return new LinkedList<>(source);
            }
        } else {
            if (targetClass == ArrayList.class) {
                return new ArrayList<>(source);
            }
            if (targetClass == LinkedList.class) {
                return new LinkedList(source);
            }
            if (targetClass == HashSet.class) {
                return new HashSet(source);
            }
            if (targetClass == LinkedHashSet.class) {
                return new LinkedHashSet(source);
            }
            if (Modifier.isAbstract(targetClass.getModifiers())) {
                Collection collection = customCreateCollection(targetClass, source.size());
                if (collection != null) {
                    collection.addAll(source);
                    return collection;
                }
                if (targetClass.isAssignableFrom(ArrayList.class)) {
                    return new ArrayList<>(source);
                }
                if (targetClass.isAssignableFrom(LinkedHashSet.class)) {
                    return new LinkedHashSet(source);
                }
                return null;
            }
            try {
                Constructor defCt = null;
                for (Constructor ct : targetClass.getConstructors()) {
                    if (Modifier.isPublic(ct.getModifiers())) {
                        switch (ct.getParameterCount()) {
                            case 0:
                                defCt = ct;
                                break;
                            case 1:
                                Class paramType = ct.getParameterTypes()[0];
                                if (paramType == Collection.class) {
                                    return (Collection) ct.newInstance(source);
                                } else if (paramType == List.class) {
                                    return (Collection) ct.newInstance(toList(source));
                                }
                                break;
                            default:
                        }
                    }
                }
                if (defCt != null) {
                    Collection c = (Collection) defCt.newInstance();
                    c.addAll(source);
                    return c;
                }
            } catch (Exception ignored) {
            }
        }
        return null;
    }