public static void main(String[] args) {
    // TODO Auto-generated method stub
    int price = 0;
    int sum = 0;
    int count = 1;
    System.out.print("输入余额");
    int money = scanner();
    System.out.println("一共" + money + "元");
    String [][] arrarr = {
            {"1.小米","1999"},
            {"2.苹果","2999"},
            {"3.联想","3999"},
            {"4.vivo","4999"}
    };
    
    System.out.println("==================");
    for(int i = 0; i < arrarr.length; i ++) {
        count ++;
    }
    
    for(int i = 0; i < arrarr.length; i ++) {
        for(int j = 0; j < arrarr[i].length; j ++)
            System.out.print(arrarr[i][j]);
        System.out.println();
    }
    System.out.println("==================");
    System.out.println("请选择商品序号");
    System.out.print("0 结算");
    
    while(true) {
        int num = scanner();
        if(num < count && num > 0) {
            System.out.print("请继续选择商品序号");
            price = total(arrarr,num);
            sum = sum + price;
        }
        else if (num == 0){
            System.out.println("==================");
            System.out.println("一共" + sum + "元");
            if(money(money, sum) >= 0) {
                System.out.print("您还剩余 ：" + money(money, sum) + "元");
                break;
            }
            else {
                System.out.println("余额不足，请充值");
            }
        }
        else {
            System.out.print("请输入正确商品序号");
            continue;
        }
    }

}

public static int scanner() {
    Scanner sc = new Scanner(System.in);
    int num = sc.nextInt();
    return num;
}

public static int total(String [][] arrarr, int num) {
    int result = Integer.parseInt(arrarr[num-1][1]);
    int sum = 0;
    sum = sum + result;
    return sum;
}

public static int money(int mon, int total) {
    int m = 0;
    m = mon - total;
    return m;
}

}

=========================
其中字符串转整形baidu了一下，可以用 Integer.parseInt（String）函数表示

2022.10.25