Java在必定範圍內生成隨機數

import java.util.ArrayList;
import java.util.Random;

public class Randomnum {
    public ArrayList Randonum(int max,int listlength ) {
        Random random=new Random();
        int count=0;
        ArrayList list=new ArrayList();
        while (count<listlength){
            int getrandom=random.nextInt(max)+1;
            if (!list.contains(getrandom)){
                list.add(getrandom);
                count++;
            }
        }
        return list;
    }
}