Overriding Methods

AP Computer Science A· difficulty 2/5

public abstract class Shape {
    public abstract double area();
}
public class Circle extends Shape {
    private double r;
    public Circle(double radius) { r = radius; }
    // no area method defined
}

What is the result of compiling Circle?

A
$Compiles fine; area() returns 0$
B
$Compiles but throws RuntimeException$
C
$Compile error: Circle must implement area() or be declared abstract$
check_circle
D
$Compiles only with a warning$

Explanation

A non-abstract subclass of an abstract class must implement all inherited abstract methods. Circle does not implement area(), so it must either implement it or be declared abstract.

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