class ZooInfo {
    private static volatile int counter = 0;

    public static void main(String args[]) {
        final String lineSeparator = System.lineSeparator();
        new Thread(() -> {
            for (int i = 0; i < 500; i++) ZooInfo.counter++;
        }).start();
    
        final StringBuilder builder = new StringBuilder();
        while (ZooInfo.counter < 100) {
            builder.append("Not reached yet").append(lineSeparator);
        }
    
        builder.append("Reached!");
        System.out.println(builder.toString());
    }
}