java 初学之面向对象设计 三角形，圆等设计
首先要对面向对象有一定了解，下面利用继承与派生的方式来演示java的面向对象过程；
创建一个java工程，添加一个新的pakage:Shapec;
添加一个新类，写入代码
/** To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package Shapec;/**
*
* @author Administrator
*/
//抽象类，图形借口
public abstract class Shape {
public static double PI = Math.PI; //π=3.1415926
public abstract double GetArea(); //计算面积
public abstract double GetLong();//计算周长
}
第二部，继承与派生，
新建5个新的类，分别命名为：J_Circle， J_FiveS ，J_Ponit，J_Triangle，J_Rectangle
其中 J_Ponit 为坐标点类。下面给出各个代码：
/** To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package Shapec;
/**
*
* @author Administrator
*/
public class J_Circle extends Shape {
public double m_r;
public double m_x , m_y;
public J_Circle(double r)
{
m_x = m_y = 0;
m_r = r;
}
public J_Circle(double m_r, double m_x, double m_y) {
this.m_r = m_r;
this.m_x = m_x;
this.m_y = m_y;
}
public J_Circle(J_Ponit p,double r){
m_x = p.m_x;
m_y = p.m_y;
m_r = r;
}
// 计算面积
public double GetArea() {
return (Shape.PI * m_r * m_r);
}
// 计算周长
public double GetLong() {
return (2 * PI * m_r);
}
@Override
public String toString() {
return("圆\n"+"面积为：" + GetArea() + ";\n周长为："+ GetLong());
}
}
/** To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package Shapec;
/**
*
* @author Administrator
*/
public class J_FiveS extends Shape {
private double E;
public double m_a;
public J_Ponit a;
public J_Ponit b;
public J_Ponit c;
public J_Ponit d;
public J_Ponit e;
public J_FiveS( J_Ponit a, J_Ponit b, J_Ponit c, J_Ponit d, J_Ponit e) {
this.E = 1.72;
this.m_a = J_Ponit.GetLongC(a, b);
this.a = a;
this.b = b;
this.c = c;
this.d = d;
this.e = e;
}
// 五边形一个点坐标和图形中心的坐标
public J_FiveS(J_Ponit a, J_Ponit o){
this.E = 1.72;
double t = J_Ponit.GetLongC(a, o);
m_a = Math.sqrt(2 * t * t * (1 - Math.cos(72 *( Math.PI / 180))));
}
public J_FiveS(double a) {
this.E = 1.72;
this.m_a = a;
}
@Override
public double GetArea() {
return E*m_a*m_a;
}
@Override
public double GetLong() {
return 5*m_a;
}
@Override
public String toString() {
return("五边形 \n"+"面积为：" + GetArea() + ";\n周长为："+ GetLong());
}
}
/** To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package Shapec;
/**
*
* @author Administrator
*/
public class J_Ponit {
public double m_x;
public double m_y;
public J_Ponit(double m_x, double m_y) {
this.m_x = m_x;
this.m_y = m_y;
}
public J_Ponit() {
m_x = 0;
m_y = 0;
}
public J_Ponit(J_Ponit p) {
m_x = p.m_x;
m_y = p.m_y;
}
public void SetX(double x){
m_x = x;
}
public void SetY(double y){
m_y = y;
}
public static double GetLongC(J_Ponit left,J_Ponit right){
return Math.sqrt(Math.pow((left.m_x - right.m_x),2) + Math.pow((left.m_y - right.m_y), 2));
}
@Override
public String toString() {
return ("x="+m_x+",y="+m_y);
}
}
J_Ponit
/** To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package Shapec;
/**
*
* @author Administrator
*/
public class J_Triangle extends Shape{
public double m_a;
public double m_b;
public double m_c;
private double m_p;
public J_Ponit a,b,c;
private void Culatep(){
m_p = (m_a + m_b + m_c) / 2;
}
public J_Triangle( J_Ponit a, J_Ponit b, J_Ponit c) {
this.a = new J_Ponit(a);
this.b = new J_Ponit(b);
this.c = new J_Ponit(c);
double a1 = J_Ponit.GetLongC(b,c);
double b1 = J_Ponit.GetLongC(a,c);
double c1 = J_Ponit.GetLongC(a,b);
if((a1 + b1) > c1 && (a1 - b1) < c1){
m_a = a1;
m_b = b1;
m_c = c1;
}
else{
m_a = m_b = m_c = 0;
}
Culatep();
}
// 正三角型
public J_Triangle(double x) {
m_a = x;
m_b = x;
m_c = x;
Culatep();
}
// 等腰三角形
public J_Triangle(double a ,double x) {
if((a + x) >x && (a - x) < x){
m_a = a;
m_b = m_c = x;
}
else{
m_a = m_b = m_c = 0;
}
Culatep();
}
//普通三角形
public J_Triangle(double ma, double mb, double mc) {
if((ma - mb) < mc && (ma + mb) > mc){
this.m_a = ma;
this.m_b = mb;
this.m_c = mc;
}
else{
m_a = m_b = m_c = 0;
}
Culatep();
}
@Override
public double GetArea() {
return Math.sqrt(m_p*(m_p - m_a)*(m_p - m_b)*(m_p - m_c));
}
@Override
public double GetLong() {
return (m_a + m_b + m_c);
}
@Override
public String toString() {
return("三角形 \n"+"面积为：" + GetArea() + ";\n周长为："+ GetLong());
}
}
/** To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package Shapec;
/**
*
* @author Administrator
*/
public class J_Rectangle extends Shape {
//矩形四个顶点
public J_Ponit a,b,c,d;
double m_a;
double m_b;
public J_Rectangle(J_Ponit a, J_Ponit b, J_Ponit c, J_Ponit d) {
this.a = new J_Ponit(a);
this.b = new J_Ponit(b);
this.c = new J_Ponit(c);
this.d = new J_Ponit(d);
m_a = J_Ponit.GetLongC(a, b);
m_b = J_Ponit.GetLongC(a, d);
}
public J_Rectangle(double a, double b) {
m_a = a;
m_b = b;
}
// 获得边长
public double GetSide_one(){
return m_a;
}
public double GetSide_two(){
return m_b;
}
//计算面积
@Override
public double GetArea() {
return (m_a * m_b);
}
//计算周长
@Override
public double GetLong() {
return (2 * m_a + 2 * m_b);
}
@Override
public String toString() {
return("矩形 \n"+"面积为：" + GetArea() + ";\n周长为："+ GetLong());
}
}
J_Rectangle
最后在mian中调用；
/** To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package shapecu;
import Shapec.J_Rectangle;
import Shapec.J_Ponit;
import Shapec.J_Triangle;
import Shapec.J_Circle;
import Shapec.Shape;
import Shapec.J_FiveS;
/**
*
* @author Administrator
*/
public class Main {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
Shape shape[] = new Shape[4];
// 矩形坐标
J_Ponit b = new J_Ponit(1, 0);
J_Ponit c = new J_Ponit(1, 1);
J_Ponit d = new J_Ponit(0, 1);
J_Ponit a = new J_Ponit(0, 0);
shape[0] = new J_Rectangle(a, b, c, d);
//三角形坐标
J_Ponit a1 = new J_Ponit(0, 0);
J_Ponit b1 = new J_Ponit(0, 4);
J_Ponit c1 = new J_Ponit(3, 0);
shape[1] = new J_Triangle(a1, b1, c1);
// 圆坐标和半径
J_Ponit o = new J_Ponit(0, 0);
shape[2] = new J_Circle(o, 3);
// 五边形,定义边长为3；
shape[3] = new J_FiveS(3);
// 输出：
System.out.println(shape[0]);
System.out.println(shape[1]);
System.out.println(shape[2]);
System.out.println(shape[3]);
}
}
main
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