java - 替换撇号之间的所有下划线(Java，字符串)

Question

我需要替换字符串中的所有下划线，除了落在两个撇号范围内的下划线。例如:

"first_name" => "first name"
"code_numbers = '123_456'" => "code numbers = '123_456'"

我目前只是使用 .replaceAll("_", "") 丢弃所有下划线，因为它们不是很常见，但我现在想触及所有底线以防万一。

Answer 1

这应该有效(此正则表达式替换了所有 _ 后跟偶数个单引号)。当然，这需要你的报价是平衡的:

String str = "\"code_numbers = '123_456'\"";

str = str.replaceAll("(?x) " + 
               "_          " +   // Replace _
               "(?=        " +   // Followed by
               "  (?:      " +   // Start a non-capture group
               "    [^']*  " +   // 0 or more non-single quote characters
               "    '      " +   // 1 single quote
               "    [^']*  " +   // 0 or more non-single quote characters
               "    '      " +   // 1 single quote
               "  )*       " +   // 0 or more repetition of non-capture group (multiple of 2 quotes will be even)
               "  [^']*    " +   // Finally 0 or more non-single quotes
               "  $        " +   // Till the end  (This is necessary, else every _ will satisfy the condition)
               ")          " ,   // End look-ahead
                       "");      // Replace with ""