String.split()分割字符串，转义字符

偏执的太偏执、 2022-02-23 11:44 477阅读 0赞

1、String.split()

String有个方法是分割字符串  .split()。但是有写字符串是需要转义才能分割，不然就会出错。

需要转义的字符串：.  $  |   (   )  \[   \{   ^  ?  \*  +  \\\\      共12个特殊字符，遇到以这些字符进行分割字符串的时候，需要在这些特殊字符前加双反斜杠 \\\\

例如：

str.split("\\\\.")

str.split("\\\\$")

str.split("\\\\|")

str.split("\\\\(")

str.split("\\\\)")

str.split("\\\\\[")

str.split("\\\\\{")

str.split("\\\\^")

str.split("\\\\?")

str.split("\\\\\*")

str.split("\\\\+")

str.split("\\\\\\\\")

2、源码：

public String[] split(String regex) { 
               return split(regex, 0); 
           } 
       public String[] split(String regex, int limit) { 
       /* fastpath if the regex is a 
       (1)one-char String and this character is not one of the 
       RegEx's meta characters ".$|()[{^?*+\\", or 
       (2)two-char String and the first char is the backslash and 
       the second is not the ascii digit or ascii letter. 
       */ 
       char ch = 0; 
       if (((regex.value.length == 1 && 
       ".$|()[{^?*+\\".indexOf(ch = regex.charAt( 0)) == - 1) || 
       (regex.length() == 2 && 
       regex.charAt( 0) == '\\' && 
       (((ch = regex.charAt( 1))- '0')|( '9'-ch)) < 0 && 
       ((ch- 'a')|( 'z'-ch)) < 0 && 
       ((ch- 'A')|( 'Z'-ch)) < 0)) && 
       (ch < Character.MIN_HIGH_SURROGATE || 
       ch > Character.MAX_LOW_SURROGATE)) 
       { 
       int off = 0; 
       int next = 0; 
       boolean limited = limit > 0; 
       ArrayList<String> list = new ArrayList<>(); 
       while ((next = indexOf(ch, off)) != - 1) { 
       if (!limited || list.size() < limit - 1) { 
       list.add(substring(off, next)); 
       off = next + 1; 
       } else { // last one 
       //assert (list.size() == limit - 1); 
       list.add(substring(off, value.length)); 
       off = value.length; 
       break; 
       } 
       } 
       // If no match was found, return this 
       if (off == 0) 
       return new String[]{ this}; 
       
       // Add remaining segment 
       if (!limited || list.size() < limit) 
       list.add(substring(off, value.length)); 
       
       // Construct result 
       int resultSize = list.size(); 
       if (limit == 0) 
       while (resultSize > 0 && list.get(resultSize - 1).length() == 0) 
       resultSize--; 
       String[] result = new String[resultSize]; 
       return list.subList( 0, resultSize).toArray(result); 
       } 
       return Pattern.compile(regex).split( this, limit); 
       }