Java 一个泛型方法,如何使数组转换类型后返回泛型

Question

我设计了一个泛型方法,使数组更改类型后返回

结果显示异常:class [Ljava.lang.Object; cannot be cast to class [Ljava.lang.Integer;
实际上返回的是Object[]类型,请问应该如何改正?

测试代码:

        String[] cs3 = new String[] { "123", "321" };
        Integer[] cs3s = convert(cs3, Integer[].class);
        System.out.println(Arrays.toString(cs3s));
        List<Boolean> list4 = new ArrayList<>();
        list4.add(true);
        list4.add(false);
        Boolean[] list4s = convert(list4, Boolean[].class);
        System.out.println(Arrays.toString(list4s));

方法代码:

public static <T> T convert(@NotNull Object obj, Class<T> itemClass) {
        if (obj.getClass() == itemClass) return (T) obj;
        String itemClassName = itemClass.getName();
        if (itemClassName.startsWith("[")) {
            if (itemClassName.charAt(1) == 'L') {
                try {
                    Class<?> clazz = Class.forName(itemClassName.substring(2, itemClassName.length() - 1));
                    Constructor<?> type = getConstructor(clazz, "java.lang.String");
                    if (type == null) throw new TypeException("不支持的转换类型");
                    if (obj instanceof Collection) {
                        List<Object> list = ((List<Object>) obj);
                        //    Object[] result = new Object[list.size()];
                        for (int i = 0; i < list.size(); i++) {
                            list.set(i, type.newInstance(String.valueOf(list.get(i))));
                        }
                        return (T) list.toArray();
                    } else {
                        Object[] objs = ((Object[]) obj);
                        Object[] result = new Object[objs.length];
                        for (int i = 0; i < objs.length; i++) {
                            result[i] = type.newInstance(String.valueOf(objs[i]));
                        }
                        return (T) result;
                    }
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | InvocationTargetException e) {
                    throw new RuntimeException(e);
                }
            } else if (itemClassName.charAt(1) == '[') {
                throw new TypeException("不支持一维以上数组转换类型");
            } else {
                throw new TypeException("不支持基元类型转换");
            }
        } else {
            throw new TypeException("测试用,仅支持一维度数组");
        }
    }
public static Constructor<?> getConstructor(@NotNull Class<?> itemClass, @NotNull String item) {
        Constructor<?> type = null;
        for (var con : itemClass.getConstructors()) {
            Class<?>[] parameterTypes = con.getParameterTypes();
            if (parameterTypes.length == 1 && parameterTypes[0].getName().equals("java.lang.String")) {
                type = con;
            }
        }
        return type;
    }

Answer 1

自己已解决,以下代码,泛型数组即可返回指定数组类型:

            Object[] objs = obj instanceof Collection ? ((Collection<?>) obj).toArray() : (Object[]) obj;
            Class<?> clazz = itemClass.getComponentType();
            Object array = Array.newInstance(clazz, objs.length);
            Object[] arrays = (Object[]) array;