Creating References Using Inheritance Hierarchies

AP Computer Science A· difficulty 3/5

public class A {}
public class B extends A {
    public void greet() { System.out.print("hi"); }
}
// Usage:
A obj = new A();
if (obj instanceof B) {
    ((B) obj).greet();
} else {
    System.out.print("not B");
}

What is printed?

A
$not B$
check_circle
B
$ClassCastException$
C
$hi$
D
$Compile error$

Explanation

obj is a plain A, not a B, so instanceof B is false. The else branch prints "not B".

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