восьмая лаба Java

//полиномы передаются через файлы polynom1 и polynom 2, одна строка - один моном - сначала коэф, через пробел степень, каждый моном на //отдельной строке
//Polynom.java
package com.company;

import java.util.ArrayList;

public class Polynom
{

    public Polynom(){}

    public Polynom(int degree, int koef)
    {
        for(int i = 0; i <= degree; ++i) arr.add(i == degree ? koef : 0);
    }

    public Polynom(ArrayList<Integer> val) {
        arr = val;
    }

    public  Polynom(Polynom val){arr = val.arr;}

    private Polynom multiplication(Polynom right)
    {
        Polynom temp = new Polynom();

        for (int i = 0; i < arr.size(); ++i)
            for (int j = 0; j < right.arr.size(); ++j)
                temp.add(i + j, arr.get(i) * right.arr.get(j));

        return temp;
    }

    private Polynom sum(Polynom right)
    {
        Polynom temp = new Polynom();

        switch (Integer.compare(arr.size(),right.arr.size()))
        {
            case 0:
                for(int i =0; i < arr.size(); ++i)
                    temp.add(i,arr.get(i)+right.arr.get(i));
                break;
            case 1:
                temp = right;
                for (int i =0; i < arr.size(); ++i)
                    temp.add(i,arr.get(i));
                break;
            case -1:
                temp = new Polynom(arr);
                for(int i =0; i < right.arr.size(); ++i)
                    temp.add(i,right.arr.get(i));
                break;
        }
        return temp;
    }

    public static Polynom sum(Polynom left, Polynom right)
    {
        return  new Polynom(left).sum(right);
    }

    public static Polynom multiplication(Polynom left,Polynom right)
    {
        return new Polynom(left).multiplication(right);
    }


    public  Polynom add(int degree, int koef)
    {
        if(arr.size() > degree)
            arr.set(degree, koef + arr.get(degree));
        else
            for(int i = arr.size(); i <= degree;++i) arr.add( i == degree ? koef : 0 );
        return this;
    }

    @Override
    public String toString()
    {
        final StringBuffer sb = new StringBuffer("<");
        for(int i = arr.size() - 1; i > 0; --i) sb.append(arr.get(i) != 0 ? arr.get(i) + "x^" + i +" ":"");
        return sb.append(">").toString();
    }

    private ArrayList<Integer> arr = new ArrayList<>();
}

//Main.java
package com.company;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args)
    {
        Polynom a = new Polynom();
        Polynom b = new Polynom();

        try(FileInputStream fin = new FileInputStream("C:\\Users\\Василий\\IdeaProjects\\lab 08\\src\\polynom1"))
        {
            BufferedReader br = new BufferedReader(new InputStreamReader(fin));
            String strLine ;
            while ((strLine = br.readLine()) != null)
                try
                {
                    a.add(new Integer(strLine.split(" ")[1]), new Integer(strLine.split(" ")[0]));
                }
                catch (NumberFormatException ex)
                {
                    System.err.println(ex.getMessage() + " Should be a number");
                    System.exit(1);
                }
        }
        catch (IOException ex)
        {
            System.err.println(ex.getMessage());
        }

        try(FileInputStream fin = new FileInputStream("C:\\Users\\Василий\\IdeaProjects\\lab 08\\src\\polynom2"))
        {
            BufferedReader br = new BufferedReader(new InputStreamReader(fin));
            String strLine ;
            while ((strLine = br.readLine()) != null)
                try
                {
                    b.add(new Integer(strLine.split(" ")[1]), new Integer(strLine.split(" ")[0]));
                }
                catch (NumberFormatException ex)
                {
                    System.err.println(ex.getMessage() + " Should be a number");
                    System.exit(2);
                }

        }
        catch (IOException ex)
        {
            System.err.println(ex.getMessage());
        }



       System.out.println(a + " * " + b + " = " + Polynom.multiplication(a,b));
        System.out.println(a + " + " + b + " = " + Polynom.sum(a,b));
    }
}