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求方程的根：使用package语句将计算根的方法封装在一个有包名的类中，包名是tom.jiafei，类名是SquareEquation。编写一个SunRise的主类，该主类使用import语句引入tom.jiafei包中的SquareEquation。
package tom.jiafei;
public class SquareEquation {
double a,b,c;
double root1,root2;
boolean boo;
public SquareEquation(double a,double b,double c) {
this.a=a;
this.b=b;
this.c=c;
if(a!=0)
boo=true;
else
boo=false;
}
public void getRoots() {
if(boo) {
System.out.println("是一元2次方程");
double disk=b*b-4*a*c;
if(disk>=0) {
root1=(-b+Math.sqrt(disk))/(2*a);
root2=(-b-Math.sqrt(disk))/(2*a);
System.out.printf("方程的根:%f,%f\n",root1,root2);
}
else {
System.out.printf("方程没有实根\n");
}
}
else {
System.out.println("不是一元2次方程");
}
}
public void setCoefficient(double a,double b,double c) {
this.a=a;
this.b=b;
this.c=c;
if(a!=0)
boo=true;
else
boo=false;
}
}
import tom.jiafei.*;
public class SunRise {
public static void main(String args[]) {
SquareEquation equation=new SquareEquation(4,5,1);
equation.getRoots();
equation.setCoefficient(-3,4,5);
equation.getRoots();
}
}
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