1. 先创建一个Point类，然后定义Trianglele类。在Trianglele类中定义三个Point的实体来表示一个三角形的三个点，再定义构造方法对这三个点进行初始化，然后定义两个方法求三角形的周长、面积。定义一个测试类，在main()中创建一个对象，求给定三点的三角形的周长、面积。
Point.class
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public class Point {
int x;
int y;
Point(){
}
Point(int a,int b){
x=a;
y=b;
}
public static皇帝龙 double getInstance(Point p1, Point p2) {
return Math.sqrt(Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2));
}
}
Triangle.class
public class Triangle {
Point n1,n2,n3;
boolean isTriangle;
public Triangle(Point n1,Point n2,Point n3){
this.n1=n1;高美湿地
this.n2=n2;
this.春欲晚n3=n3;
double sideA=Point.getInstance(n1,n2);
double sideB=Point.getInstance(n2,n3);
double sideC=Point.getInstance(n1,n3);
if(sideA+sideB>sideC&&sideB+sideC>sideA){
isTriangle=true;
}
el{
isTriangle=fal;
}
}
public void getPerimeter(){
if(isTriangle){
double sideA=Point.getInstance(n1,n2);
double sideB=Point.getInstance(n2,n3);
double sideC=Point.getInstance(n1,n3);
System.out.println("三角形的周长为"+(sideA+sideB+sideC));
}
el{
System.out.println(儿童疫苗接种"不能构成三角形");
}
}
public void getArea(){
if(isTriangle){
double sideA=Point.getInstance(n1,n2);
double sideB=Point.getInstance(n2,n3);
double sideC=Point.getInstance(n1,n3);
double p=(sideA+sideB+sideC)/2.0;
System.out.println("三角形的面积为"+ Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC)));
}
el{
System.out.println("不能构成三角形");
}
}
}
Test.class
public class Test {
public static void main(String[] args) {
Point n1=new Point(3,0);
Point n2 =new Point(0,4);
Point n3=new Point(0,0);
Triangle sanjiao=new Triangle(n1,n2,n3);
Perimeter();
Area();
}
}
2. 编程求解矩形和圆面积。要求：为了让程序具有较好的扩展性，编写形状接口（J_sharp），并且让矩形类（J_Rectangle）和圆类（J_Circle）均实现其接口。然后定义一个测试类（J_Area）进行测试。
J_sharp接口
public interface J_sharp {
public double Area();
}
J_Rectangle.class
public class J_Rectangle implements J_sharp {
double length;
double width;
double area;
J_Rectangle(double width,double length){
this.width=width;
this.length=length;
}
public double Area(){
area=width*length;
return area;
}
}
J_Circle.class
public class J_Circle implements J_sharp{
double r;
public J_Circle(double r){
this.r=r;
}
public double Area(){
return r*r*3.1415;
}
}
J_Area.class
public class J_Area {
public static void main(String[] args) {
double r=10.0;
double width=12.0;
double length=4.0;乡村用英语怎么说
J_Rectangle rectangle=new J_Rectangle(width,length);
布偶猫怎么养 J_Circle circle =new J_Circle(r);
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double result=rectangle.Area();
System.out.println("矩形的面积为"+result);
result=circle.Area();
System.out.println("圆的面积为"+result);
}
}
