Java record -44-object Array traps

The following is a very simple program, but there are unexpected traps:

public static void Main (string[] args) {ArrayList list = new ArrayList ();        List.add (New Integer (1));        List.add (New Integer (2));               integer[] ins = (integer[]) List.toarray ();        object[] ins = List.toarray ();        for (int i=0;i<ins.length;i++) {System.out.println (ins[i]); }    }

The above program can be executed, no problem.

But the line of code that is commented on runs throws the following exception:

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; Cannot is cast to [Ljava.lang.Integer; At My.arraylist.ArrayListTest.main (arraylisttest.java:16)

integer[] ins = (integer[]) List.toarray ();

The List.toarray () method returns the object[] array, object[] array cast to the integer[] array, the literal understanding is no problem, the compile time is OK, but the runtime throws an exception, which is why?

1. The above example confirms that the object[] array cannot be coerced into a integer[] array without doubt.

2. The integer object inherits the object, but the integer[] array does not inherit the object[] array, and the literal understanding does not seem to make sense.

3. A deeper understanding of the object[] array is not just about storing an integer object, it can also store objects such as strings and so on.

4. If an object[] array holds an integer object, also holds a string object, and a Boolean object is stored, then there is a problem when the object[] array is cast to the integer[] array. You cannot convert a string and a Boolean object to an Integer object.
   

Java record -44-object Array traps