Abstract classes do not implicitly add abstract modifier
Even if abstract modifier was added, the Engine class compiles fine and the code prints ON OFF
If we do not make changes to turnON() and turnOFF() methods, then Operator class will not compile.
class abstract class Operator {
protected void turnON();
protected void turnOFF();
}
class EngineOperator extends Operator {
public final void turnON() {
System.out.println("ON");
}
public final void turnOFF() {
System.out.println("OFF");
}
}
class Engine {
Operator m = new EngineOperator();
public void operate() {
m.turnON();
m.turnOFF();
}
}
public class Test {
public static void main(String[] args) {
Engine carEngine = new Engine();
carEngine.operate();
}
}
Answer is C:
There are 2 ways to print output as ON/OFF:
1) methods turnON() and turnOFF() need to be declared as abstract.
or
2) methods turnON() and turnOFF() need to be declared as protected void turnON() {some code here...}.
Only then, EngineOperator class will be able to override these methods.
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and the code fragment:
jduarte
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