/** * Equation.java */package cn.edu.uibe.oop;/** * 计算一元二次方程的根 * @author TongQiang * */public class Equation { double a,b,c; //方程的系数 double x1,x2; //两个根 double r;
//实部 double v;
//虚部 int type;
//0表示一个根，1表示两个实根，2表示两个复数的根 public Equation(double a,double b,double c){this.a = a;this.b = b;this.c = c; } private double delta(){return b*b-4*a*c; } public void calculate(){double d = delta();if(Math.abs(d)0){ type = 1; x1 = (-b+Math.sqrt(d))/(2*a); x2 = (-b-Math.sqrt(d))/(2*a);}else{ type = 2; r =-b/(2*a); v = Math.sqrt(-d)/(2*a);} } public void showResult(){switch(type){case 0: System.out.println("方程只有一个实根，x1=x2="+x1); break;case 1: System.out.println("方程有两个实根，分别是：x1="+x1+"\tx2="+x2); break;case 2: System.out.println("方程有两个复数根，分别是："+r+"+"+v+"i,\t"+r+"-"+v+"i"); break;} } public static void main(String[] args) {Equation eq1 = new Equation(1,2,2);eq1.calculate();eq1.showResult();Equation eq2 = new Equation(1,-2,1);eq2.calculate();eq2.showResult();Equation eq3 = new Equation(1,6,5);eq3.calculate();eq3.showResult(); }}
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