Java的对象与类,继承
题目1.Java类的建立与使用
设计一个用来描述汽车的类，使用类的非静态成员变量来表示汽车的车主姓名、当前的速率和当前方向盘的转向角度，使用类的非静态成员方法来表示改变汽车的速率和停车两个操作。
package test;
public class t1 {
private String Name;//车主姓名
private float Speed;//当前车速
private float Degree;//当前方向盘转向角度
public t1(String Name){
this.Name = Name;
}
public t1(String name,float speed,float degree){
this(name);
this.Speed = speed;
this.Degree = degree;
}
public String getName(){//车主姓名访问
return Name;
}
public float getDegree(){//当前方向盘转向角度访问
return Degree;
}
public float getSpeed(){//当前车速访问
return Speed;
}
public void changeSpeed(float Speed){//提供改变当前的车速
this.Speed = Speed;
}
public void stop(){//提供停车
this.Speed = 0;
}
public static void main(String[] args){
t1 car = new t1("小明：",200f,25f);
System.out.println("车主姓名：" +car.getName());
System.out.println("当前车速："+car.getSpeed());
}
}
题目2.Java类的建立与使用
定义一个类实现银行帐户的概念，包括的变量有"帐号"和"存款余额"，包括的方法有"存款"、"取款"、"查询余额"和”显示帐号”。定义主类，创建帐户类的对象，并完成相应操作。
package test;
import java.util.*;
public class t2 {
private String User;//账户
private double Money;//当前余额
private double add;//存款金额
private double subtract;//取款金额
public t2(String User){
this.User = User;
}
public t2(String User,double Money){
this(User);
this.Money = Money;
}
public String getUser(){//用户账号访问
return User;
}
public double getMoney(){//当前余额访问
return Money;
}
public void addMoney(double Money){//存款
this.Money+=Money;
}
public void subtractMoney(double Money){//取款
this.Money-= Money;
}
public static void main(String[] args){
t2 bank = new t2("12345678",34537.876);
System.out.println("账号：" +bank.getUser());
System.out.println("当前余额："+bank.getMoney());
Scanner in = new Scanner(System.in);
System.out.println("输入存款金额");
double add = in.nextDouble();
System.out.println("输入取款金额");
double sub = in.nextDouble();
bank.addMoney(add);
System.out.println("存款后，当前余额：" +bank.getMoney());
bank.subtractMoney(sub);
System.out.println("取款后，当前余额："+bank.getMoney());
}
}
题目3. 继承
设计一个类Shape（图形）包含求面积和周长的area()方法和perimeter()方法以及设置颜色的方法SetColor()，并利用Java多态技术设计其子类Circle（圆形）类、Rectangle（矩形）类和Triangle（三角形）类，并分别实现相应的求面积和求周长的方法。每个类都要覆盖toString方法。海伦公式：三角形的面积等于s(s-a)(s-b)(s-c)的开方，其中s=(a+b+c)/2。
package test;
public class t3 {
public static void main(String[] args) {
Circle c = new Circle(4,"white");
System.out.println(c.toString());
Rectangle r = new Rectangle(4, 5, "white");
System.out.println(r.toString());
Triangle t = new Triangle(3,4,5,"black");
System.out.println(t.toString());
} }
abstract class Shape{
String color="red";
public double area(){
return -1;
}
public double perimeter(){
return -1;
}
public String SetColor(String a){
return color=a;
}
}
class Circle extends Shape{
private double bj;
Circle(){
bj=1;
}
Circle(double i,String col){
bj=i;
super.color=super.SetColor(col);
}
public void setBj(double b){
this.bj = b;
}
public double area(){
return Math.PI * bj * bj; }
public double perimeter(){
return Math.PI * bj * 2;
}
public String toString(){
return( "圆的半径为" + this.bj+"圆的面积："+this.area()+"圆的周长："+this.perimeter());
} }
class Rectangle extends Shape{
double h;
double w;
Rectangle(){
}
Rectangle(double hi,double wi,String col){
h=hi;
w=wi;
super.color=super.SetColor(col);
}
public double area(){
return h * w; }
public double perimeter(){
return (w+h)* 2;
}
public String toString(){
return( "矩形的长为" + this.h+"矩形的宽为"+this.w+"矩形的面积:"+this.area()+"矩形的周长："+this.perimeter());
} }
class Triangle extends Shape{
double a;
double b;
double c;
Triangle(){
}
Triangle(double aa,double bb,double cc,String col){
a=aa;
b=bb;
c=cc;
super.color=super.SetColor(col);
}
public double area(){
double s =((a+b+c)/2);
return Math.sqrt (s*(s-a)*(s-b)*(s-c));
}
public double perimeter(){
return a+b+c;
}
public String toString(){
return( "三角形的长为" + this.a+"三角形的宽为"+this.b+"三角形的斜边"+this.c+"三角形的面积:"+this.area()+"三角形的周长："+this.perimeter());
}
}