这是一个使用 Java 8 流的解决方案:

Here's a solution using Java 8 streams:

String line = "1,21,33";
List<Integer> ints = Arrays.stream(line.split(","))
        .map(Integer::parseInt)
        .collect(Collectors.toList());

或者，使用循环，只需使用 parseInt:

String line = "1,21,33";
for (String s : line.split(",")) {
    System.out.println(Integer.parseInt(s));
}

如果你真的想重新发明***，你也可以这样做:

If you really want to reinvent the wheel, you can do that, too:

String line = "1,21,33";
for (String s : line.split(",")) {
    char[] chars = s.toCharArray();
    int sum = 0;
    for (int i = 0; i < chars.length; i++) {
        sum += (chars[chars.length - i - 1] - '0') * Math.pow(10, i);
    }
    System.out.println(sum);
}