Java OCA OCP Practice Question 1432

Question

How many lines of the following class do not compile? 

1:  package mypkg; 
2:  abstract class Bird { 
3:     protected int sing; 
4:     protected abstract int m(); 
5:     int sing() { 
6:        return sing; 
7:     } /*from   w  w  w . j  a v a 2s.c  o  m*/
8:  } 
9:  public class MyBird extends Bird { 
10:    int m() { 
11:       sing() += 10; 
12:       return super.m()+1; 
13:       return 10; 
14:    } 
15: }
  • A. None, the class compiles without issue.
  • B. One
  • C. Two
  • D. Three
  • E. Four
  • F. Five


D.

Note

Line 10 does not compile because the override reduces the visibility of an inherited method, with the package-private modifier being more restrictive than the protected modifier.

Line 11 does also not compile, since the left-hand side of a compound assignment operator must be used with a variable, not a method.

Line 12 does not compile because super.

m() is inherited as an abstract method in the MyBird class, meaning the parent class has no implementation.

Option D is the correct answer.




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