Юшкин ЯП7

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws FileNotFoundException {
        PrintWriter printWriter1=new PrintWriter(new File("First.txt"));
        PrintWriter printWriter2=new PrintWriter(new File("Second.txt"));
        PrintWriter printWriter3=new PrintWriter(new File("Third.txt"));
        WorkingClass.replace(() -> { //запись в отдельный файл квадратов чисел
            Scanner scanner =new Scanner(new File("Ввод.txt"));
            while (scanner.hasNext()){
                int val=scanner.nextInt();
                printWriter1.println(String.format("%s²=%s",val,(int)Math.pow(val,2)));
            }
            printWriter1.close();
            scanner.close();
        });
        WorkingClass.replace(() -> { //подсчет среднего значения чисел из файла
            Scanner scanner =new Scanner(new File("Ввод.txt"));
            int sum=0;
            int counter=0;
            while (scanner.hasNext()){
                sum+=scanner.nextInt();
                counter++;
            }
            printWriter2.println("Среднее значение: "+(double)(sum/counter));
            printWriter2.close();
            scanner.close();
        });
        WorkingClass.replace(() -> { //запись в отдельный файл кубов чисел
            Scanner scanner =new Scanner(new File("Ввод.txt"));
            while (scanner.hasNext()){
                int val=scanner.nextInt();
                printWriter3.println(String.format("%s³=%s",val,(int)Math.pow(val,3)));
            }
            printWriter3.close();
            scanner.close();
        });

    }
}
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import java.io.FileNotFoundException;

public class WorkingClass {
    public static void replace(WorkingInterface workingInterface) throws FileNotFoundException {
        workingInterface.replace();
    }
}

////////////

import java.io.FileNotFoundException;

public interface WorkingInterface {
    void replace() throws FileNotFoundException;
}