Programming are endless.

// LottoNumber.class
 

public class LottoNumber {

	public static void main(String[] args) {
		
		HashSet set = new HashSet();
		
		
		while(set.size()<=6) {
			set.add((int)(Math.random() * 44) + 1);
		}
		
		for(int a : set) {
			System.out.println(a);
		}
		
	}
}