Solution:Step 1: Understand reference typeAn Appliance reference cannot call subclass-specific methods directly.Step 2: Use downcastingCast the Appliance reference to WashingMachine to access startWash().Step 3: Correct syntax((WashingMachine) applianceRef).startWash();Final Answer:Cast the Applianc

[Solved] Given these classes:class Appliance { void powerOn() { System.out.... } }How can you invoke startWash() on an Appliance reference that actually points to a WashingMachine object? | Java

Java - Polymorphism

Given these classes:

class Appliance { void powerOn() { System.out.println("Appliance powered on"); } }
class WashingMachine extends Appliance { void powerOn() { System.out.println("Washing machine powered on"); } void startWash() { System.out.println("Washing started"); } }

How can you invoke startWash() on an Appliance reference that actually points to a WashingMachine object?

ACall startWash() directly on the Appliance reference

BCast the Appliance reference to WashingMachine and then call startWash()

CCreate a new WashingMachine object and call startWash() on it

DOverride startWash() in Appliance class

Step-by-Step Solution

Solution:

Step 1: Understand reference type
An Appliance reference cannot call subclass-specific methods directly.
Step 2: Use downcasting
Cast the Appliance reference to WashingMachine to access startWash().
Step 3: Correct syntax
((WashingMachine) applianceRef).startWash();
Final Answer:
Cast the Appliance reference to WashingMachine and then call startWash() -> Option B
Quick Check:
Subclass methods require downcast from superclass reference [OK]

Quick Trick: Downcast superclass ref to subclass to access subclass methods [OK]

Common Mistakes:

Calling subclass method on superclass reference without cast
Creating new object unnecessarily
Trying to override non-existent methods

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More Java Quizzes

Given these classes:

Step 1: Understand reference type

Step 2: Use downcasting

Step 3: Correct syntax

Final Answer:

Quick Check:

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