Access to resource which is not thread-safe

import static java.lang.System.out;

/**

* Main-class

*

* @author orochi_100

* @version 01.04.2020

*/

public class Main {

private static int num = 0;

/** In this main-method we are trying to increment an integer-variable to 20.000 with 2 threads in the first half and 1 thread in the other half */

public static void main(String[] args) {

out.println("Hello World!");

new Thread(() -> {

for (int i = 0; i < 10_000; i++) incrementNum();

}).start();

for (int i = 0; i < 10_000; i++) incrementNum();

if (num == 10_000) out.println(num);

num = 0;

for (int i = 0; i < 10_000; i++) incrementNum();

for (int i = 0; i < 10_000; i++) incrementNum();

out.println(num);

}

/**Just for the sake of incrementing the static variable <code>num</code>*/

public static void incrementNum() {

num++;

}

}