Question

I’m making a Java program that can solve the roots using the quadratic equation by giving a, b, and c.

Here is the main code:

//main file

class Call
{
       public static void main(String args [])
    {
            double a=Double.parseDouble(args[0]);
            double b=Double.parseDouble(args[1]);
            double c=Double.parseDouble(args[3]);

            Receiver r = new Receiver(".");
            if (r.determine(a,b,c)=true)
            {
                    double root1=r.Root;
                    double root2=r.Root2;
                    System.out.println("The first root is +root1");
                    System.out.println("The second root is +root2");


            }
            else
            {
                    System.out.println("Not a number");
            }
    }
 }

Now here’s the class I’m trying to call but couldn’t.

   class Receiver
    {
    public boolean determine(double a, double b, double c)
    {
            double value=b*b-4*a*c;
                    if (value<0)
                            return false;
                    else
                            return true;
    }

    public double Root(double a, double b, double c)
    {
            double value=b*b-4*a*c;
            double root=(-b+ Math.sqrt(value))/(2*a);
            return root;
    }

    public double Root2(double a, double b, double c)
    {
            double value=b*b-4*a*c;
            double root2=(-b- Math.sqrt(value))/(2*a);
            return root2;
    }
    }

I made sure that I compiled the Receiver.java already. But when I compile Call.java, I get this error:

Call.java:14:error:cannot find symbol
      Receiver r= new Receiver();
      symbol: class Receiver
      location: class Call

Answer 1

Note that I haven’t found constructor public Receiver(String arg), and you’re using it like this, aren’t you missing that?

If you’re compiling those by yourself from command line ensure, these steps:

Create package with those class

// top of Call.java
package com.mypackage.app;

// top of Receiver.java
package com.mypackage.app;

Compile those files so that package is created in class structure
(this will create folders in current location like /com/mypackage/app/)

javac -d . Call.java Receiver.java

Run the Call class from current location by it’s package name

java com.mypackage.app.Call