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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