Java StringTokenizer，空空标记

Question

我正在尝试将一个字符串拆分为 29 个标记...... stringtokenizer 不会返回空标记。我尝试过 string.split，但我相信我做错了什么：

String [] strings = line.split(",", 29);

示例输入：

10150,15:58,23:58,16:00,00:00,15:55,23:55,15:58,00:01,16:03,23:58,,,,,16:00,23:22,15:54,00:03,15:59,23:56,16:05,23:59,15:55,00:01,,,,
10155,,,,,,,,,,,07:30,13:27,07:25,13:45,,,,,,,,,,,07:13,14:37,08:01,15:23
10160,10:00,16:02,09:55,16:03,10:06,15:58,09:48,16:07,09:55,16:00,,,,,09:49,15:38,10:02,16:04,10:00,16:00,09:58,16:01,09:57,15:58,,,,

Answer 1

如果您希望保留尾随的空字符串，但又不想给出最大值的幻数，请使用负数限制：

line.split(",", -1)

If line.equals("a,,c"),然后line.split(",", -1)[1].isEmpty();它不是null。这是因为当 "," 为分隔符时，",," 两个分隔符之间有一个空字符串，而不是 null。

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Example:

使用上面的解释，考虑以下示例： ",,"

尽管您可能期望 ","、null 和 <代码>“，”。

实际结果是 ",", "" 和 ","

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If you want null instead of empty strings in the array returned by split, then you'd have to manually scan the array and replace them with null. I'm not sure why s == null is better than s.isEmpty(), though.

另请参阅

• Java String.indexOf 和空字符串

Answer 2

在 Apache Commons Lang 库中使用 StringUtils.splitPreserveAllTokens()

Answer 3

如果您希望保留空令牌，string.split将无法令人满意地工作。 StringTokenizer 也不起作用。
我提供了以下方法，可能对你有帮助

public static String[] splitTotokens(String line, String delim){
  String s = line;
  int i = 0;

  while (s.contains(delim)) {
  s = s.substring(s.indexOf(delim) + delim.length());
      i++;
  }
  String token = null;
  String remainder = null;
  String[] tokens = new String[i];

  for (int j = 0; j < i; j++) {
    token = line.substring(0, line.indexOf(delim));
    //System.out.print("#" + token + "#");
    tokens[j] = token;
    remainder = line.substring(line.indexOf(delim) + delim.length());
    //System.out.println("#" + remainder + "#");
    line = remainder;
    }

  return tokens;`  
 }

Answer 4

use this org.springframework.util.StringUtils

org.springframework.util.StringUtils.delimitedListToStringArray(data, delimit);

此类提供了一些简单的功能，提供了易于使用的方法来在分隔字符串（例如 CSV 字符串）与集合和数组之间进行转换。

Answer 5

如果您希望保留空令牌，string.split() 将无法令人满意地工作。 StringTokenizer 也将不起作用。我提供了以下方法，可能对你有帮助：

public static String[] splitTotokens(String line, String delim){
    String s = line;
    int i = 0;

    while (s.contains(delim)) {
        s = s.substring(s.indexOf(delim) + delim.length());
        i++;
    }
    String token = null;
    String remainder = null;
    String[] tokens = new String[i];

    for (int j = 0; j < i; j++) {
        token = line.substring(0, line.indexOf(delim));
        // System.out.print("#" + token + "#");
        tokens[j] = token;
        remainder = line.substring(line.indexOf(delim) + delim.length());
        //System.out.println("#" + remainder + "#");

        line = remainder;
    }
    return tokens;
}