Given: 1. interface Pastry { 2. void getIngredients(); 3. } 4. abstract class Cookie implements Pastry {} 5. 6. class chocolateCookie implements Cookie { 7. public void getIngredients() {} 8. } 9…

The correct answer is A. The compilation fails due to an error in line 6. Option A is correct because Cookie is an abstract class, not an interface, and Java only allows implements to be used with interfaces. Line 6 should read class chocolateCookie extends Cookie - using implements with a class is a compile-time error, regardless of whether the…

Java Object-Oriented Approach

Question

Given:
interface Pastry {
void getIngredients();
}
abstract class Cookie implements Pastry {}
class chocolateCookie implements Cookie {
public void getIngredients() {}
}
class CoconutChocolateCookie extends ChocolateCookie {
void getIngredients(int X) {}
}

Which is true?

Options

AThe compilation fails due to an error in line 6.
BThe compilation succeeds.
CThe compilation fails due to an error in line 4.
DThe compilation fails due to an error in line 10.
EThe compilation fails due to an error in line 7.
FThe compilation fails due to an error in line 2.
GThe compilation fails due to an error in line 9.

How the community answered

(54 responses)

A
81% (44)
B
6% (3)
C
2% (1)
F
2% (1)
G
9% (5)

Explanation

Option A is correct because Cookie is an abstract class, not an interface, and Java only allows implements to be used with interfaces. Line 6 should read class chocolateCookie extends Cookie - using implements with a class is a compile-time error, regardless of whether the class is abstract or concrete.

Why the distractors are wrong:

C (line 4) is valid - abstract classes are permitted to implement an interface without providing implementations for its methods; that obligation passes down to concrete subclasses.
E (line 7) is valid - public void getIngredients() correctly implements the interface contract with equal or wider visibility.
F (line 2) is valid - interface methods are implicitly public abstract, so the declaration is legal.
D (line 10) shows an overload (different parameter), not an error per se, but the code never reaches that point due to the earlier failure.
G (line 9) references ChocolateCookie (capital C) while line 6 defines chocolateCookie (lowercase c) - this would also be an error, but the compiler halts at line 6 first.
B is simply wrong because the code does not compile.

Memory tip: Think of the keywords by relationship type - extends is for class-to-class (one "extends" the family tree), implements is strictly for class-to-interface. If you ever see a class implements another class, flag it immediately.

Topics

#interface vs abstract class#implements vs extends#inheritance#compilation error

Community Discussion

No community discussion yet for this question.

Full 1Z0-819 Practice