Program to compute roots of quadratic equation in Java

class P5
{
public static void main(String args[])
{
double a , b , c , d , e ;
double temp , r1 , r2 ;
int select ;


a=2;b=3;c=6;
temp = (b * b) - (4 * a * c) ;

if (temp > 0)
select = 0 ;
else
if (temp == 0)
select = 1 ;
else
select = 2 ;


switch (select)
{
case 0 :
temp = Math.sqrt (temp) ;
r1 = (-b + temp) / (2 * a) ;
r2 = (-b - temp) / (2 * a) ;
System.out.println("The roots are Real and Unequal.\n");
System.out.println("The roots are : "+r1+"  "+r2);
break ;
case 1 :
r1 = -b / (2 * a) ;
r2 = r1 ;
System.out.println("The roots are Real and Equal.\n");
System.out.println("The roots are : "+r1+"  "+r2);
break ;
case 2 :
temp = -temp ;
temp = Math.sqrt (temp) ;
temp = temp / (2 * a) ;
r1 = -b / (2 * a) ;
System.out.println("The roots are Real and Imaginary.\n");
System.out.println("The roots are : "+r1+"+ j"+temp+" , "+r1+"- j"+temp);
break ;
}


}
}