class Demo3{    public static void main(String[] args) {        //数组的初始化        int[] a = new int[] {12,13,14,15};        int[] b = {12,13,14,15};        //数组的便利        for(int i = 0;i<4;i++) {            System.out.println(a[i]);        }        for(int i = 0;i