Object cast to Object[]

[Howard Hu]

why Object can be casted to Object[] but other Class type can not
be casted to array of that class?
Object o = new Object();
Object[] ob = (Object[])o;
MyClass c = new MyClass();
MyClass c[] =(MyClass[]) c;
Howard

[Panagiotis Varlagas]

Because an Object[] is (polymorphically) an Object (everything is polymorphically an object), whereas MyClass[] is not polymorphically a class. The compiler does not check what variable o is pointing to; it just knows that it is (polymorphically) an Object. So, when you attempt to cast it to an Object[] the compiler "says" to itself" "Well, o just *might* be referring to an Object[], so let's accept it, and wait till run-time to find out.
Hope this helps,
Panagiotis.

Originally posted by Howard Hu:
why Object can be casted to Object[] but other Class type can not
be casted to array of that class?

Object o = new Object();
Object[] ob = (Object[])o;

MyClass c = new MyClass();
MyClass c[] =(MyClass[]) c;

Howard

[Howard Hu]

Panajiotis,
Yes, it makes sense. Here is another question related to this.
Object o = new int[10];
Base class Object refers to an array. So now we are able to use subclass's overidding methods and subclass-added methods. What are those method that the object o here can use? What is that subclass definition for an array?
--Howard

[Panagiotis Varlagas]

Every array type (e.g. int[]) is considered to be a subtype of Object. You can invoke any method of Object on o (toString(), hashCode(), getClass() etc.). Also, every array type adds a public final field (length) to what it inherits from Object.
You cannot extend an array type yourself. The only way to do so is to extend the component class. (e.g. MyString[] is polymorhically a String[]). However, this would not add *any* functionality to the array type itself.