求解Java题目！！

public class Yugi{
    public static String[] getRandomTeachers(String[] teachers, int n){
        String[] arr = new String[n];
        String tmp = ",";
        for(int i = 0; i < n; i++){
            int rand = (int)(Math.random() * teachers.length);
            if(!tmp.contains("," + rand + ",")){
                arr[i] = teachers[rand];
                tmp += rand + ",";
            }else{
                i--;
            }
        }
        return arr;
    }
    public static void main(String[] args){
        String[] arr = getRandomTeachers(new String[]{"joey","yugi","kaiba","kensou"}, 3);
        System.out.println(Arrays.toString(arr));
    }
}