Java开发练习2，类与对象

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(intspeed))，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。

public class Vehicle {int speed;int size;public Vehicle(int speed, int size) {// TODO Auto-generated constructor stubthis.speed = speed;this.size = size;}public int getSpeed() {return speed;}public void setSpeed(int speed) {this.speed = speed;}public int getSize() {return size;}public void setSize(int size) {this.size = size;}void move(){}int speedUp(){return speed+10;} int speedDown(){return speed-5;}}

public class VehicleTest {public static void main(String[] args) {// TODO Auto-generated method stubVehicle  v = new Vehicle(10,5);System.out.println("速度："+v.getSpeed());System.out.println("体积："+v.getSize());System.out.println("加速："+v.speedUp());System.out.println("减速："+v.speedDown());}}

2.打印当前时间。学习使用Date类和Calendar类

import java.util.Calendar;import java.util.Date;public class Time {public static void main(String[] args) {// TODO Auto-generated method stubDate time=new Date();System.out.println(time);//获取时间Calendar cal =Calendar.getInstance();     cal.setTime(new Date());     int year=cal.get(Calendar.YEAR);     int month=cal.get(Calendar.MONTH)+1;  //一月对应0；     int day=cal.get(Calendar.DAY_OF_MONTH);     System.out.print(" "+year+"年"+" "+month+"月"+day+"日");}}

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。

import java.util.*;public class Circle { int x; int y; double r; Circle(){ //无参构造方法  x=1;  y=1;  r=1.0; } Circle(int a,int b,int R){//有参构造方法  x=a;  y=a;  r=R;   } void Chongdie(Circle c) {  //判定重叠  if(x==c.x&&y==c.y&&r==c.r)   System.out.println("c1和c2重叠");  else   System.out.println("c1和c2不重叠"); }}import java.util.Scanner;class CircleTest { public static void main(String[] args) {  Scanner input=new Scanner(System.in);  int a=input.nextInt();  int b=input.nextInt();  int R=input.nextInt();  Circle c1=new Circle();  Circle c2=new Circle(a,b,R);  c1.Chongdie(c2); }}

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。

public class Phone {SIM sim=new SIM();public SIM getSim() {    return sim;}public void setSim(SIM sim) {    this.sim = sim;}public void show(){    System.out.println(sim.getNumber());}}public class SIM {int number;public long getNumber() {    return number;}public void setNumber(int number) {    this.number = number;}}public class zuhe {public static void main(String[] args) {// TODO Auto-generated method stub    SIM sim=new SIM();    sim.setNumber(123456789);    Phone phone=new Phone();    phone.setSim(sim);    phone.show();    System.out.println("换号");    SIM simnew=new SIM();    simnew.setNumber(987654321);    phone.setSim(simnew);    phone.show();}}

5.用类描述CPU硬盘

public class CPU {int speed;public int getSpeed() {return speed;}public void setSpeed(int speed) {this.speed = speed;}}

public class HardDisk {int amount;public int getAmount() {return amount;}public void setAmount(int amount) {this.amount = amount;}}

public class PC {CPU cpu;HardDisk HD;public CPU getCpu() {return cpu;}public void setCpu(CPU cpu) {this.cpu = cpu;}public HardDisk getHD() {return HD;}public void setHD(HardDisk hD) {this.HD = hD;}void Show() {System.out.println("CPU频率"+cpu.getSpeed());System.out.println("硬盘容量"+HD.getAmount());}}

package org.gerrysu.Test5;public class Test {public static void main(String[] args) {// TODO Auto-generated method stubCPU cpu = new CPU();cpu.setSpeed(2200);HardDisk disk = new HardDisk();disk.setAmount(200);PC pc = new PC();pc.setCpu(cpu);pc.setHD(disk);pc.Show();}}