Array casting: ClassCastException

Question

import java.util.Vector;
public class X
public static void main(String args[])
     //first part
String [] array = {"1","2", "3"};
Object [] objs = array;
array = (String[])objs;
for( int i =0 ; i < array.length; i++)
System.out.println(array);
     //second part
Vector v = new Vector();
v.add("1");
v.add("2");
v.add("3");
objs = v.toArray();
array = (String[])objs;
for( int i =0 ; i < array.length; i++)
System.out.println(array[i]);
Why does the first part work properly but the second cause ClassCastException? Even if an array was instantiated as Object[] in toArray method casting MUST be ok. I work with an instances in array but not with array. An array only contains an objects I work with. It's only technical structure! Why does it cause ClassCastException?

Answer 1

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Yes. I know it. The point is WHY it was done in this
way? What can I do with the type of array? NONE. The
actual information is CONTAINED in array. So array
is only technical structure. I can't derive it, it has
no virtual mechanisms. The actual objects I need are
stored in array. The type of them is important. It
looks like miss of language structure.
The basic question here is a fundamental part of polymorphism - you cannot cast an Object into one that it is not.
Object a = new Object();
String b = (String) a;That code will also compile, but it is just as incorrect as your code. The problem is that "a" will never be a String. There may be ways to convert it into a String, but the object a will always be of type "Object" and never extend String, so it cannot be cast.
Similarly, an array of type Object[] will always be of type Object[]. It cannot be cast to String[], because it will never have String[] as a superclass, if you will. The rules for working with arrays are exactly the same as working with the object which is the base type of the array.
In order to be able to do a cast from Object[] to String[], there would have to be a runtime check which would ensure that every element in the Object[] was, in fact, a String. But the cast check in the compiler is just looking up the extends and implements chains. If you want to implement a runtime cast, Java basically leaves that up to you.
And as has been mentioned, they do let you provide the array to be used as well.