Java 为什么 String.split 需要管道分隔符才能转义？
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Why does String.split need pipe delimiter to be escaped?
提问by starthis
I am trying to parse a file that has each line with pipe delimited values. It did not work correctly when I did not escape the pipe delimiter in split method, but it worked correctly after I escaped the pipe as below.
我正在尝试解析一个文件，该文件的每一行都带有管道分隔值。当我没有在 split 方法中转义管道分隔符时，它没有正常工作，但是在我转义管道后它正常工作，如下所示。
private ArrayList<String> parseLine(String line) {
ArrayList<String> list = new ArrayList<String>();
String[] list_str = line.split("\|"); // note the escape "\" here
System.out.println(list_str.length);
System.out.println(line);
for(String s:list_str) {
list.add(s);
System.out.print(s+ "|");
}
return list;
}
Can someone please explain why the pipe character needs to be escaped for the split()method?
有人可以解释为什么需要为该split()方法转义管道字符吗？
采纳答案by Louis Wasserman
String.splitexpects a regular expression argument. An unescaped |is parsed as a regex meaning "empty string or empty string," which isn't what you mean.
String.split需要一个正则表达式参数。未转义的|被解析为正则表达式，意思是“空字符串或空字符串”，这不是您的意思。
回答by dlamblin
Because the syntax for that parameter to splitis a regular expression, where in the '|' has a special meaning of OR, and a '\|' means a literal '|' so the string "\\|" means the regular expression '\|' which means match exactly the character '|'.
因为要拆分的那个参数的语法是一个正则表达式，其中的“|” 有 OR 的特殊含义，还有一个 '\|' 表示文字“|” 所以字符串“\\|” 表示正则表达式'\|' 这意味着完全匹配字符“|”。
回答by Ravinath
You can simply do this:
你可以简单地这样做：
String[] arrayString = yourString.split("\|");
