Java 产生一个大于等于200，小于300的随机数，且是10的整数倍

 

public class Random200_300 {
    public static void main(String[] args) {
        int r1 = 0;
        while (true) {
            r1 = (int)(Math.random() * 10) * 10 + 200;
            if ((200 <= r1) && (r1 < 300)) {
                System.out.println(r1);
            } else {
                System.out.println("Error!");
                break;
            }
            
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}