public static final String[] getRandomStrings(int n) {
		Set<String> set = new HashSet<String>();
		String[] strs = new String[n];
		while (true) {
			// һظַ
			String temp = String.valueOf((char) ('a' + (new Random()
					.nextInt(26))));
			set.add(temp);
			if (set.size() == n)
				break;
		}
		
		Iterator<String> iterator = set.iterator();
		int i = 0;
		while(iterator.hasNext()){
			strs[i] = iterator.next();
			i++;
		}
		return strs;
	}