Creating References Using Inheritance Hierarchies

AP Computer Science A· difficulty 3/5

public class A {
    public String f() { return "A"; }
}
public class B extends A {
    public String f() { return "B"; }
    public String g() { return "g"; }
}
A x = new B();
System.out.println(x.g());

What happens?

A
$Compile-time error: g not in A$
check_circle
B
$Prints g$
C
$Runtime error$
D
$Prints null$

Explanation

Method calls are checked against the declared type. A has no <code> g() </code>, so this fails to compile.

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