Given:interface Foo {}class Alpha implements Foo { }class Beta extends Alpha {} class Delta extends Beta {public static void main( String[] args) { Beta x = new Beta(); // insert code here}}Which code, inserted at line 16, will cause a java.lang.ClassCastException?

technology programming languages

  1. Alpha a = x;

  2. Foo f= (Delta)x;

  3. Foo f= (Alpha)x;

  4. Beta b = (Beta)(Alpha)x;

Show answer
Correct Option: A,B,C,D

AI Explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) Alpha a = x; - This option is incorrect because it is a valid assignment. Since Beta extends Alpha, you can assign an object of type Beta to a variable of type Alpha.

Option B) Foo f = (Delta)x; - This option is incorrect because it is a valid assignment. Since Delta extends Beta and implements Foo, you can assign an object of type Beta to a variable of type Foo by casting it to Delta.

Option C) Foo f = (Alpha)x; - This option is incorrect because it is a valid assignment. Since Beta extends Alpha and implements Foo, you can assign an object of type Beta to a variable of type Foo by casting it to Alpha.

Option D) Beta b = (Beta)(Alpha)x; - This option is incorrect because it is a valid assignment. Since Beta extends Alpha, you can assign an object of type Beta to a variable of type Beta by casting it to Alpha.

None of the given options will cause a java.lang.ClassCastException. The correct answer is None (None of the given options will cause a java.lang.ClassCastException).

Note: A java.lang.ClassCastException occurs when you try to cast an object to a type that it is not compatible with. In this case, all the assignments are valid and do not involve incompatible types, so a ClassCastException cannot occur.

Find more quizzes: