第四周作业

1.请定义一个交通工具(Vehicle)的类，其中有: 

属性：速度(speed)，体积(size)等 

方法：移动(move())，设置速度(setSpeed(int speed))，设置体积（setSize(int size)）加速speedUp(),减速speedDown()等 

在测试类Vehicle中的main()中实例化一个交通工具对象，通过方法给它初始化speed,size的值，并打印出来。另外，调用加速，减速的方法对速度进行改变。

package week2;

public class Vehicle {

private int speed,size;

public static void main(String[] args) {
// TODO Auto-generated method stub
Vehicle vehicle = new Vehicle();
vehicle.move();
vehicle.setSize(10);
vehicle.setSpeed(100);
vehicle.speedUp();
vehicle.speedDown();
System.out.println(vehicle.toString());
}

//移动方法
public void move(){
System.out.println("移动");
}

//设置速度
public void setSpeed(int speed) {
this.speed = speed;
}

//设置体积
public void setSize(int size) {
this.size = size;
}

//加速
public void speedUp(){
System.out.println("加速");
}

//减速
public void speedDown(){
System.out.println("减速");
}

@Override
public String toString() {
return "Vehicle [speed=" + speed + ", size=" + size + "]";
}

}

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2.打印当前时间。学习使用Date类和Calendar类。（教材P194页）

package week2;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class TestDate {

public static void main(String[] args) {
// TODO Auto-generated method stub
Date date = new Date();
System.out.println(date);

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println(simpleDateFormat.format(date));

Calendar calendar = Calendar.getInstance();
String str = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).format(calendar.getTime());
System.out.println(str);
}

}

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3.以Point类为基础，定义一个平面中的Circle类： 

1、编写一个无参的构造函数； 

2、编写一个有参的构造函数； 

3、在主函数中调用无参的构造函数生成圆的实例c1，调用有参的构造函数生成圆的实例c2，调用实例方法判断c1和c2是否相重叠。

package week2;

public class Circle {

private double radius;

public Circle(){
radius = 2.0;
}

public Circle(double radius){
this.radius = radius;
}
}

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package week2;

public class TestTotal {

public static void main(String[] args) {
Circle circle1 = new Circle();
Circle circle2 = new Circle(3.0);
if (circle1 == circle2) {
System.out.println("是同一个实例");
}else{
System.out.println("不是同一个实例");
}
}

}

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4.编写代码模拟手机与SIM卡的组合关系。 

要求： 

SIM卡类负责创建SIM卡； 

Phone类负责创建手机； 

手机可以组合一个SIM卡； 

手机可以更换其中的SIM卡。

package week3;

public class Phone {

private SIM sim;

public SIM getSim() {
return sim;
}

public void setSim(SIM sim) {
this.sim = sim;
}

Phone(){
System.out.println("我是Phone");
}
}

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package week3;

public class SIM {

public SIM() {
// TODO Auto-generated constructor stub
System.out.println("我是SIM");
}
}

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package week3;

public class TestPhone {

public static void main(String[] args) {
// TODO Auto-generated method stub
SIM sim = new SIM();
Phone phone = new Phone();
phone.setSim(sim);
}

}

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4.

package week3;

public class CPU {public CPU() {
// TODO Auto-generated constructor stub
}
private int speed;

public int getSpeed() {
return speed;
}

public void setSpeed(int speed) {
this.speed = speed;
}
}

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package week3;

public class HardDisk {

private int amount;

public int getAmount() {
return amount;
}

public void setAmount(int amount) {
this.amount = amount;
}

}

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package week3;

public class PC {

private CPU cpu;
private HardDisk hardDisk;

public HardDisk getHardDisk() {
return hardDisk;
}

public void setHardDisk(HardDisk hardDisk) {
this.hardDisk = hardDisk;
}

public CPU getCpu() {
return cpu;
}

public void setCpu(CPU cpu) {
this.cpu = cpu;
}

public void show(){
System.out.println("CPU速度为:"+getCpu().getSpeed()+" 硬盘容量为:"+getHardDisk().getAmount());
}

}

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package week3;

public class Test {

public static void main(String[] args) {
// TODO Auto-generated method stub
CPU cpu = new CPU();
cpu.setSpeed(2200);
HardDisk hardDisk = new HardDisk();
hardDisk.setAmount(200);
PC pc = new PC();
pc.setCpu(cpu);
pc.setHardDisk(hardDisk);
pc.show();
}

}

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5.–定义一个圆类(Circle)，其所在的包为bzu.info.software；定义一个圆柱类Cylinder，其所在的包为bzu.info.com；定义一个主类A，其所在的包也为bzu.info.com，在A中生成一个Cylinder对象，并输出其体积。编译并运行该类。 

–试着改变求体积方法的访问权限，查看并分析编译和运行结果 

–把Cylinder类和A类置于不同的包中，通过对求体积方法设置不同的访问权限，查看并分析编译和运行结果

package bzu.info.com;

/**
* 圆柱类
* @author Lenovo_PC
*
*/
public class Cylinder {

private int radius;
private int hight;

public Cylinder(int radius, int hight) {
super();
this.radius = radius;
this.hight = hight;
}

public double calu(){
return Math.PI*Math.pow(radius, 2)*hight;
}
}

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package bzu.info.com;

public class A {

public static void main(String[] args) {
// TODO Auto-generated method stub
Cylinder cylinder = new Cylinder(2,3);
System.out.println(cylinder.calu());
}

}

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