java编程题，求答案，急求。

如题所述

Engine.java

package com.nemo.test;

/**
 * 发动机
 */
public class Engine {

private float paiqiliang; // 排气量

public float getPaiqiliang() {
return paiqiliang;
}

public void setPaiqiliang(float paiqiliang) {
this.paiqiliang = paiqiliang;
}

public void startEngine() {
System.out.println("发动机启动！！！");
}

public void stopEngine() {
System.out.println("发动机关闭！！！");
}

}

SteeringWheel.java

package com.nemo.test;

/**
 * 方向盘
 */
public class SteeringWheel {

private String caizhi; // 材质

public String getCaizhi() {
return caizhi;
}

public void setCaizhi(String caizhi) {
this.caizhi = caizhi;
}

public void xuanzhuanSteeringWheel() {
System.out.println("选中方向盘！！！");
}

}

Wheel.java

package com.nemo.test;

/**
 * 车轮
 */
public class Wheel {

private String brand; // 品牌

public String getBrand() {
return brand;
}

public void setBrand(String brand) {
this.brand = brand;
}

public void chongqi() {
System.out.println("给车轮充气！！！");
}

}

Car.java

package com.nemo.test;

/**
 * 汽车
 */
public class Car {

private String brand; // 汽车品牌
private Engine engine; // 发动机
private Wheel wheel; // 车轮
private SteeringWheel steeringWheel; // 方向盘

public String getBrand() {
return brand;
}

public void setBrand(String brand) {
this.brand = brand;
}

public Engine getEngine() {
return engine;
}

public void setEngine(Engine engine) {
this.engine = engine;
}

public Wheel getWheel() {
return wheel;
}

public void setWheel(Wheel wheel) {
this.wheel = wheel;
}

public SteeringWheel getSteeringWheel() {
return steeringWheel;
}

public void setSteeringWheel(SteeringWheel steeringWheel) {
this.steeringWheel = steeringWheel;
}

public Car(Engine engine, Wheel wheel, SteeringWheel steeringWheel) {
this.brand = "东风";
this.engine = engine;
this.wheel = wheel;
this.steeringWheel = steeringWheel;
}

public Car() {
}

public static void main(String[] args) {
Engine engine = new Engine(); // 造发动机
engine.setPaiqiliang(1.5f); // 设置发动机排气量
SteeringWheel steeringWheel = new SteeringWheel(); // 造方向盘
steeringWheel.setCaizhi("黄金"); // 设置方向盘材质
Wheel wheel = new Wheel(); // 造车轮
wheel.setBrand("兰博基尼"); // 设置车轮品牌

Car car = new Car(engine, wheel, steeringWheel); // 造汽车
wheel.chongqi(); // 给车轮充气
engine.startEngine(); // 启动发动机
steeringWheel.xuanzhuanSteeringWheel(); // 选中方向盘
System.out.println(car.getBrand() + "牌子的汽车开动了！！！");
}

}