Random generate number

I am trying to make my own random number generator, but I was constantly getting the same values, I solved this with the sleep function, but how can I do without using sleep please help, I shared my code below.

My Random class

private int x;
private long ms;
public int random(int a) throws InterruptedException
{
    ms = System.currentTimeMillis();
    x=(int)(ms%a);
    Thread.sleep(1);
    return (int)x;
}

Main

 for(int i=0;i<100;i++)
    {
        System.out.println(rnd.random(10));
    }