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 stub
this.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 stub
Vehicle  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 stub
Date 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());
}

}

packa
946d
ge org.gerrysu.Test5;

public class Test {

public static void main(String[] args) {
// TODO Auto-generated method stub
CPU 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();

}

}