不明白一下代码的      for (car car : carForRent)    为什么是 car car : carForRent     

car [ ] carForRent={new passengerCar(1,"奥迪A4",500,4),new passengerCar(2,"马自达6",400,4),

                                          new pickUp(3,"皮卡雪6",450,4,2),new passengerCar(4," 金龙 ",800,20),

                                          new trunk(5,"松花江",400,4),new trunk(6,"依维柯",1000,20)};

            System.out.println("序号"+"\t"+"汽车名称"+"\t"+"租金"+"\t"+"\t"+"容量");

 //打印输出可供租的汽车清单

            for (car car : carForRent) {

                //用instanceOf来测试左边类型的对象是否是右边类型的实例，返回值为Boolean

                if(car instanceof passengerCar){

                    //若它是客车类型的实例，则打印出客车应该有的属性值，这里注意强转，否则不会出现

                    //passengerCar类的CarCapacity属性

                    System.out.println(car.getCarNumber()+"\t"+car.getCarName()+"\t"+car.getCarRentMoney()

                                                  +"/天"+"\t"+"载人:"+((passengerCar)car).getCarCapacity()+"人");

                }

                if(car instanceof pickUp){

                    System.out.println(car.getCarNumber()+"\t"+car.getCarName()+"\t"+car.getCarRentMoney()

                                                  +"/天"+"\t"+"载人:"+((pickUp)car).getCarCapacity()+"人"+"\t"

                                                  +"载货:"+((pickUp)car).getCarCarryCargo()+"吨");

                }

                if(car instanceof trunk){

                    System.out.println(car.getCarNumber()+"\t"+car.getCarName()+"\t"+car.getCarRentMoney()

                                                  +"/天"+"\t"+"载货:"+((trunk)car).getCarCarryCargo()+"吨");

                }

            }