JSP学习笔记(六十三)：java中生成随机数

1.生成0~9之间的随机数

    public static void main(String[] args) {
        Random rnd = new Random();
        System.out.println(rnd.nextInt(10));
    }

 

2.生成1~9之间的随机数

    public static void main(String[] args) {
        Random rnd = new Random();
        System.out.println(rnd.nextInt(9) + 1);

    }

 

3.生成1~9之间不重复的随机数

    public static void main(String[] args) {
        int [] seed = {1,2,3,4,5,6,7,8,9};
        int [] ranArr = new int [9];   
        Random ran = new Random();
        for(int i = 0 ; i<seed.length ; i++){   
            int j = ran.nextInt(seed.length-i);
            ranArr [i] = seed [j];
            seed [j] = seed [seed.length-1-i];
            System.out.println ("ranArr[" + i + "]" + ":" + ranArr[i]);   
        } 
    }

或者

    public static void main(String[] args) {
        List<Integer> list = new ArrayList<Integer>();   
        
        for(int i = 1; i <= 9; i++){   
            list.add(i);   
        }   
  
        Collections.shuffle(list);   
           
        for(Integer i : list){   
            System.out.println(i);   
        }   
    }