Question

编写一个Shape类，具有属性：周长和面积； 定义其子类三角形和矩形，分别具有求周长的方法。

编写一个Shape类，具有属性：周长和面积；
定义其子类三角形和矩形，分别具有求周长的方法。
定义主类E，在其main方法中创建三角形和矩形类的对象，
并赋给Shape类的对象a、b，使用对象a、b来测试其特性。

Answer 1

package com.zhang.na;
public class Shape1 {
protected float width;
protected float height;
public double area() {
return width * height;
}
public double zhouCh() {
return width + height;
}
public float getWidth() {
return width;
}
public void setWidth(float width) {
this.width = width;
}
public float getHeight() {
return height;
}
public void setHeight(float height) {
this.height = height;
}
}

import com.zhang.na.Shape1;

public class Rectangle extends Shape1 {
public double zhouCh() {
return 2 * (width + height);
}
}

import com.zhang.na.Shape1;

public class Triangle extends Shape1 {
double a;
public double zhouCh(){
return (2*a+width);
}
public double getA() {
return a;
}
public void setA(double a) {
this.a = a;
}

}

public class E {

public static void main(String[] args) {
System.out.println("请设定矩形长、宽：");

Rectangle rec=new Rectangle();
Triangle tri=new Triangle();
rec.setHeight(1);
rec.setWidth(2);
System.out.println(rec.zhouCh());
System.out.println(rec.area());
System.out.println("请设定三角形底和高：");
tri.setWidth(3);
tri.setHeight(4);
tri.setA(2);
System.out.println(tri.area()/2);
System.out.println(tri.zhouCh());
}
}

写的不是很好，仅供参考

Answer 2

1. interface Shape
{
public abstract double area();
public abstract double perimeter();
public abstract double display();
}

2. class Circle implements Shape
{
int x;//横坐标
int y;//纵坐标
double a;//半径
public Circle (int x,int y,double a)//构造函数
{
this.x=x;
this.y=y;
this.a=a;
}
public double area()
{
return 3.14*a*a;
}

public double perimeter()
{
return 2*3.14*a;
}

public void display()
{
System.Out.println("此圆的圆心为a("+this.x+","+this.y+")");
System.Out.println("此圆的半径为r="+this.a);

}
}

3. 4. 就不写了,与圆类似,就多了个drow()函数,你可以去找找这个函数的实现

5. public static void main(String[]args)throws IOException
{
Circle C=new Circle(2,3,5);
System.out.println("所求圆的面积S="+C.area());
System.out.println("所求圆的周长L="+C.perimeter());
C.display();
//其他的测试一样
}

Answer 3

public class E {
public static void main(String[] args) {
Shape a=new tri();
Shape b=new rec();
System.out.println(((tri) a).gettriperi(1,5,5));
System.out.println(((rec) b).getrecperi(1,5));
}
}
class Shape{
int peri;
int area;
}
class tri extends Shape{
public int gettriperi(int x,int y,int z) {
peri=x+y+z;
return peri;
}
}
class rec extends Shape{
public int getrecperi(int x,int y) {
peri=2*(x+y);
return peri;
}
}