多选题 Given:
1. class Contact {
2. String doStuff() {return "howdy "; }
3. }
4. class Supplier extends Contact {
5. String doStuff() {return "send money "; }
6. public static void main(String[] args) {
7. Supplier s1 = new Supplier();
8. Contact c3 = new Contact();
9. Contact c1 = s1;
10. Supplier s2 = (Supplier) c1;
11. Supplier s3 = (Supplier) c3;
12. Supplier s4 = new Contact();
13. } }
Which are true? (Choose all that apply.)
A. Compilation succeeds.
B. The code runs without exception.
C. If the line(s) of code that do NOT compile (if any) are removed, the code runs without exception.
D. If the line(s) of code that do NOT compile (if any) are removed, the code throws an exception at runtime.