How to Translate working code into code with a Tester Class

I have this code: it works and it properly runs. I just do not know how to make it have 2 classes and make a call. Sorry for the beginner question. Thank you for your help.

Code :

---

import java.util.Scanner;
 
/**
    Counts the number of digits with value 7 in the 
     decimal representation of the integer n
*/
 
public class CountSevens1
{
    public static void main(String[] args)
    {
        String s = "";    
        Scanner in = new Scanner(System.in);
        System.out.print("Enter digits: ");
        int n = in.nextInt();
        s = Integer.toString(n);
 
        //your work here
        System.out.println(countDigits(s));
    }
 
    public static int countDigits(String s) 
    {
        int count = 0;
 
        for (int i = 0; i < s.length(); i++)
        {
            if (s.charAt(i) == '7') 
            {
                count++;
            }
        }
        return count;
    }
}

---

I think your question is about how to make two class files communicate with each other. At this basic level, simply create two files, put them in the same folder, compile both of them, and run the class that contains the main(String[] args).

For example, let's say we have two files: FileA and FileB. FileA contains just the main, and FileB contains method: doSomething():

Code java:

---

public class FileA {
     public static void main(String[] args) {
          FileB other = new FileB();
          other.doSomething();
     }
}

---

Code java:

---

public class FileB {
     public void doSomething() {
          return; //does nothing
     }
}

---

Now, as long as both of those files are in the same folder, are both compiled, and you run FileA, it will work with no worries.

I did what you said and i keep getting the same error. this is what i have in the tester class.[CODE]import java.util.Scanner;
public class CountSevens1Tester
{
public static void main(String[] args)
{ String s = "";
Scanner in = new Scanner(System.in);
System.out.print("Enter digits: ");
int n = in.nextInt();
s = Integer.toString(n);
CountSevens1 x = new CountSevens1();
x.countDigits();
}
}[CODE]

I now have the tester down to this:

import java.util.Scanner;
public class CountSevens1Tester
{
public static void main(String[] args)
{ String s = "";
Scanner in = new Scanner(System.in);
System.out.print("Enter digits: ");
int n = in.nextInt();
s = Integer.toString(n);
CountSevens1 x = new CountSevens1();
x.countDigits(s);
System.out.print("I do not know what to put here to return the number of sevens.");
}
}

I am not sure what to put in the last line.

What error were you getting earlier?

If you want to print out the result, you can do this (assuming CountSevens1.countDigits(s) returns an int):

Code java:

---

CountSevens1 x = new CountSevens1();
int result = x.countDigits(s)
System.out.print("Number of Sevens: "+result);

---

code removed by moderator
//this is rama krishna raju .if u like this reply me

@ramakrishnaraju
Please see The problem with spoonfeeding.