字符串数字相加

比如输入21345，求出2+1+3+4+5

• 方法一：

Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
//先把这个整数转换成字符串
String string = String.valueOf(n);

int a = 0;
int sum = 0;
for (int i = 0; i < string.length(); i++) {
    //截取每个字符串的一位数然后转乘整型，进行相加
    a = Integer.parseInt(string.substring(i,i+1));
    sum+=a;
}
System.out.println(sum);

• 方法二：

Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();

String string = String.valueOf(n);
int sum = 0;
for (int i = 0; i < string.length(); i++) {
    //把字符变成整型，然后减去48
    char s = string.charAt(i);
    sum = sum + Integer.valueOf(s)-48;
}

System.out.println(sum);