Review Questions

6.17 Given the following program, which statement is true? 
// Filename: MyClass.java
public class MyClass {
    public static void main(String[] args) {
        A[] arrA;
        B[] arrB;

        arrA = new A[10];
        arrB = new B[20];
        arrA = arrB;       // (1)
        arrB = (B[]) arrA; // (2)
        arrA = new A[10];
        arrB = (B[]) arrA; // (3)
    }
}

class A {}

class B extends A {}

Select the one correct answer.

  1. The program will fail to compile because of the assignment at (1).

  2. The program will throw a java.lang.ClassCastException in the assignment at (2) when run.

  3. The program will throw a java.lang.ClassCastException in the assignment at (3) when run.

  4. The program will compile and ...

Get Programmer's Guide to Java™ Certification, A: A Comprehensive Primer, Second Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial