java - Extract array encapsulated in an Object

Question

Let's say i have an array encapsulated in an object :

String[] strvls = { "Alessio", "Ale" };
Object container = strvls;

I want to extract back the array from the container object, how can i do ?

I know that is an array checking in this way :

if(container.getClass().isArray()) {
    //Extract the encapsulated array - How ?
}

I can't cast into a String array, because I can't know for sure that the type of the array was String[] ... So i need to cast into a generic type array, Is it possible in Java ?

Answer 1

您可以将其转换为Object[]数组：

String[] strvls = { "Alessio", "Ale" };
Object container = strvls;
if (container.getClass().isArray()) {
    Object[] data = (Object[]) container;
    System.out.println(data.length);
}

Answer 2

与 Karaszi 的回答类似，但可能有一条捷径：

if(container instanceof Object[])
  System.out.println("Array size: " + ((Object[])container).length);

重要提示：这不适用于原始数组。上面的代码有效，因为 String 派生自 Object 类。

Answer 3

你可以有这样的方法：

private static <T> T[] getArray(Object o){
    return (T[]) o;
}

这将有助于使用泛型类型，并且您可以将任何“未经检查”的编译器警告封装在此方法中。然后你可以这样做：

Object[] array = getArray(container);

如果您对类型一无所知，或者：

String[] array = getArray(container);

如果你知道它是一个字符串数组。