我需要在字符串列表中的特定字符后输入整数

Question

伙计们，我在这里遇到了问题。 我需要从字符串列表中获取字符串中的所有数字。

假设列表中的一个字符串是“Jhon [B] - 14, 15, 16” ，字符串的格式是不变的，每个字符串最多有 7 个数字，数字用“,”分隔。 我想得到"-"之后的每个数字。 我在这里真的很困惑，我尝试了我所知道的一切，但我还没有接近。

public static List<String> readInput() {
    final Scanner scan = new Scanner(System.in);
    final List<String> items = new ArrayList<>();
    while (scan.hasNextLine()) {
        items.add(scan.nextLine());
    }
    return items;
}

public static void main(String[] args) {
    final List<String> stats= readInput();
    
}

}

Answer 1

你可以...

只需使用String#indexOf和String#split （和String#trim ）之类的东西手动解析String

String text = "Jhon [B] - 14, 15, 16";
int indexOfDash = text.indexOf("-");
if (indexOfDash < 0 && indexOfDash + 1 < text.length()) {
    return;
}
String trailingText = text.substring(indexOfDash + 1).trim();
String[] parts = trailingText.split(",");
// There's probably a really sweet and awesome
// way to use Streams, but the point is to try
// and keep it simple 😜
List<Integer> values = new ArrayList<>(parts.length);
for (int index = 0; index < parts.length; index++) {
    values.add(Integer.parseInt(parts[index].trim()));
}

System.out.println(values);

哪个打印

[14, 15, 16]

你可以...

例如，为Scanner使用自定义定界符......

String text = "Jhon [B] - 14, 15, 16";

Scanner parser = new Scanner(text);
parser.useDelimiter(" - ");
if (!parser.hasNext()) {
    // This is an error
    return;
}
// We know that the string has leading text before the "-"
parser.next();
if (!parser.hasNext()) {
    // This is an error
    return;
}
String trailingText = parser.next();

parser = new Scanner(trailingText);
parser.useDelimiter(", ");
List<Integer> values = new ArrayList<>(8);
while (parser.hasNextInt()) {
    values.add(parser.nextInt());
}

System.out.println(values);

哪个打印...

[14, 15, 16]

Answer 2

或者您可以使用一种方法从字符串中提取有符号或无符号整数或浮点数。 下面的方法使用了String#replaceAll()方法：

/**
 * This method will extract all signed or unsigned Whole or floating point 
 * numbers from a supplied String. The numbers extracted are placed into a 
 * String[] array in the order of occurrence and returned.<br><br>
 * 
 * It doesn't matter if the numbers within the supplied String have leading 
 * or trailing non-numerical (alpha) characters attached to them.<br><br>
 * 
 * A Locale can also be optionally supplied so to use whatever decimal symbol 
 * that is desired otherwise, the decimal symbol for the system's current 
 * default locale is used. 
 * 
 * @param inputString (String) The supplied string to extract all the numbers 
 * from.<br>
 * 
 * @param desiredLocale (Optional - Locale varArgs) If a locale is desired for a 
 *               specific decimal symbol then that locale can be optionally 
 *               supplied here. Only one Locale argument is expected and used 
 *               if supplied.<br>
 * 
 * @return (String[] Array) A String[] array is returned with each element of 
 *               that array containing a number extracted from the supplied 
 *               Input String in the order of occurrence.
 */
public static String[] getNumbersFromString(String inputString, java.util.Locale... desiredLocale) {
    // Get the decimal symbol the the current system's locale.
    char decimalSeparator = new java.text.DecimalFormatSymbols().getDecimalSeparator();
    
    /* Is there a supplied Locale? If so, set the decimal 
       separator to that for the supplied locale       */
    if (desiredLocale != null && desiredLocale.length > 0) {
        decimalSeparator = new java.text.DecimalFormatSymbols(desiredLocale[0]).getDecimalSeparator();
    } 
    /* The first replaceAll() removes all dashes (-) that are preceeded
       or followed by whitespaces. The second replaceAll() removes all
       periods from the input string except those that part of a floating 
       point number. The third replaceAll() removes everything else except 
       the actual numbers. */
   return  inputString.replaceAll("\\s*\\-\\s{1,}","")
                      .replaceAll("\\.(?![\\d](\\.[\\d])?)", "")
                      .replaceAll("[^-?\\d+" + decimalSeparator + "\\d+]", " ")
                      .trim().split("\\s+");
}