using Atomic types in Java

Main.java

package com.company;

import java.util.concurrent.atomic.AtomicInteger;

class Account {
    private AtomicInteger balance;

    Account(int sum) {
        balance = new AtomicInteger(sum);
    }

    public int getBalance() {
        return balance.get();
    }

    public void add(int i) {
        balance.addAndGet(i);
    }

    public void rem(int i) {
        balance.addAndGet(-i);
    }
}

class Adder implements Runnable {
    private final Account acc;

    Adder(Account acc) {
        this.acc = acc;
    }

    @Override
    public void run() {
        for (int i = 0; i < 2000; i++)
            acc.add(1);
    }
}

class Minuser implements Runnable {
    private final Account acc;

    Minuser(Account acc) {
        this.acc = acc;
    }

    @Override
    public void run() {
        for (int i = 0; i < 2000; i++)
            acc.rem(1);
    }
}

public class Main {

    public static void main(String[] args) throws Exception {
        Account account = new Account(100_000);

        Thread minThr = new Thread(new Minuser(account));
        Thread addThr = new Thread(new Adder(account));
        System.out.println("Start balance = "+account.getBalance());
        System.out.println("Threads ran");
        minThr.start();
        addThr.start();

        minThr.join();
        addThr.join();
        System.out.println("End balance = "+account.getBalance());
    }
}