How can I prevent the overlapping random numbers

How would i prevent duplicating numbers from random numbers. I need to generate 5 numbers between 1 and 9 that are each different. I would often get same numbers like 23334, how can i prevent that? Any help would be great!

    int num2 = (int) Math.round((Math.random()*9) +1);
    int num1 = (int) Math.round((Math.random()*9) +1);
    int num5 = (int) Math.round((Math.random()*9) +1);
    int num3 = (int) Math.round((Math.random()*9) +1);
    int num4 = (int) Math.round((Math.random()*9) +1);