java - 不使用正则表达式从随机字符串返回所有整数的总和

Question

最近在面试中被问到这个问题(Java programming que)

返回随机字符串中所有整数的总和。

Answer 1

只需遍历字符串，一次处理一个数字。这几乎正​​是正则表达式无论如何都会做的事情:

    String testStrings[] = { "-1a2b3c", "123ab!45c", "abcdef", "0123.4",
            "dFD$#23+++12@#T1234;/.,10" };

    for (String testString : testStrings) {
        String currentNumber = "";
        int sum = 0;
        for (int i = 0; i < testString.length(); i++) {
            char currentChar = testString.charAt(i);

            // Add digits or a leading minus to "currentNumber"
            if (Character.isDigit(currentChar)
                    || (currentNumber.equals("") && currentChar == '-')) {
                currentNumber += currentChar;
            } else {
                // We've stumbled across a non-digit char.
                //Try to parse the "currentNumber" we have so far
                if (!currentNumber.equals("") && !currentNumber.equals("-"))
                    sum += Integer.parseInt(currentNumber);
                currentNumber = "";
            }
        }

        // Add the last "currentNumber" in case the string ends with a
        // number
        if (!currentNumber.equals("") && !currentNumber.equals("-"))
            sum += Integer.parseInt(currentNumber);
        System.out.println(sum);
    }

输出:

4
168
0
127
1279