public static void main(String[] args) { //配置 int[] nums = {500, 300, 200, 0}; int[] price = {200, 100, 50, 0}; //输入 Scanner sc = new Scanner(System.in); int n = sc.nextInt(); //极值判断 if (n = Integer.MAX_VALUE) { System.out.println("请输入有效的充值金额!"); return; } //区间判断 for (int i = 0; i = nums[i]) { System.out.println(n + price[i]); break; } } } 换一种写法 上面有注释 相信题主能看懂