New to Java

You know how if you generate random numbers 1 after the other they are the same/very close? This is because it has to do with a clock right? Why doesn't my following code solve the problem? Is there any way I can make random numbers so they aren't all the same?

		for(int i = 0; i<level; i++)
		{
				arr[i] = (int)(Math.random()*10);
				Thread.sleep(400);
		}