Here is a java example that finds the roots of the quadratic equation.

import java.util.*;
class QuadraticEquation
{
public static void main(String[]args){
Scanner input=new Scanner(System.in);
System.out.print("Do you want to solve an equation (y/n): ");
String st=input.next();
if(st.equals("y")){
System.out.print("Enter the value of a: ");
double a=input.nextDouble();
System.out.print("Enter the value of b: ");
double b=input.nextDouble();
System.out.print("Enter the value of c: ");
double c=input.nextDouble();

double eq=b*b-4*a*c;
double r1= -b+Math.sqrt(eq);
double r2= -b-Math.sqrt(eq);
double Root1=r1/2*a;
double Root2=r2/2*a;
System.out.println("Root 1 ="+Root1);
System.out.println("Root 2 ="+Root2);
}
else{
System.exit(0);
}
}
}