阅读以下说明和Java代码,填充程序中的空缺,将解答填入答题纸的对应栏内。
【说明】
某应急交通控制系统(TraficControlSystem)在红灯时控制各类车辆 (Vehicle)的通行,其类图如图6-1所示,在紧急状态下应急车辆在红灯时可通行,其余车辆按正常规则通行。
下面的Java代码实现以上设计,请完善其中的空缺。
【Java 代码 】
abstract class Vehicle {
public Vehicle( ) { }
abstract void run( );
};
interface Emergency {
(1) ;
(2) ;
};
class Car extends Vehicle {
public Car( ) { )
void run ( ) { /*代码略*/ }
};
class Truck extends Vehicle {
public Truck( ) { }
void run ( ) { /*代码略*/ }
};
class PoliceCar (3) {
boolean isEmergency = false;
public PoliceCar() { }
public PoliceCar(boolean b) { this.isEmergency=b; }
public boolean isEmergent( ) { return ( 4 ) ; }
public void runRedLight( ) { /*代码略*/ }
};
/*类Ambulance 、 FireEngine 实现代码略*/
public class TraficControlSystem { /*交通控制类*/
private Vehicle[ ] v = new Vehicle[24];
int numVehicles;
public void control( ) {
for (int i = 0; i < numVehicles; i++) {
if (v[i] instanceof EmErgency && ((Emergency)v[i]).
isEmergent()) {
( 5 ) .runRedLigh ( );
} else
( 6 ) .run ( ) ;
}
}
void add(Vehicle vehicle) { v[numVehicles++] = vehiclei} /*添加车辆*/
void shutDown() { /*代码略* /}
public static void main (Str :.ng [ ] args) {
TraficControlSystem tcs = new TraficControlSystem();
tcs.add(new Car()};
tcs.add(new PoliceCar();
tcs.add(new Ambulance();
tcs.add(new Ambulance(t:ue));
tcs.add(new FireEngine( :rue));
tcs.add(new Truck());
tcs.add(new FireEngine( );
tcs.control();
tcs.shutDown();
}
}