basic jAVA based on imlemetation of interface [duplicate]

This question already has an answer here:

• j2me error: class myClass is public should be declared in a file named myClass.java 2 answers

HOW TO WRITE A JAVA PROGRAM BY USING INTERFACE BY DECLARING IT PUBLIC

For instance:
import java.io.*;
import java.util.*; 
interface MyfirstInterface
{
    public String helloz="HELLO..FRIENDS";
    public void Sayzhello();
}
public class implementor implements MyfirstInterface
    {
        public void Sayzhello()
        {
            System.out.println(MyfirstInterface.helloz);
        }
        public static void main(String args[])
        {
            implementor MyfirstInterface=new implementor();
            MyfirstInterface.Sayzhello();
        }
    }
//the given program shows output :HELLO..FRIENDS
//while if by using public as like this:
import java.io.*;
import java.util.*;
public interface MyfirstInterface
{
    public String helloz="HELLO..FRIENDS";
    public void Sayzhello();
}
public class implementor implements MyfirstInterface
    {
        public void Sayzhello()
        {
            System.out.println(MyfirstInterface.helloz);
        }
        public static void main(String args[])
        {
            implementor MyfirstInterface=new implementor();
            MyfirstInterface.Sayzhello();
        }
    }

it shows like this implementor.java:3: error: class MyfirstInterface is public, should be declared in a file named MyfirstInterface.java public interface MyfirstInterface ^ 1 error how can the error be rectified