java - 删除 CSV 行的字符串引号中的逗号

Question

目前，我倾向于删除 CSV 行的字符串中的逗号。

这是我的期望

    // (1) ",123,456,"     -> ",123456,"
    // (2) ","abc,def","   -> ","abcdef","
    // (3) ","123,456","   -> ","123456","
    // (4) ","abcdef,","   -> ","abcdef","

我写了下面的代码

    String[] test = {
        "\",123,456,\"",
        "\",\"abc,def\",\"",
        "\",\"123,456\",\"",
        "\",\"abcdef,\",\""            
    };

    final Pattern commaNotBetweenQuotes = Pattern.compile("(?<!\"),(?!\")");

    for (String d : test) {
        System.out.println("O : " + d);
        String result = commaNotBetweenQuotes.matcher(d).replaceAll("");
        System.out.println("R : " + result);
    }

然而，我在情况(4)中失败了

这是我得到的输出

O : ",123,456,"
R : ",123456,"

O : ","abc,def","
R : ","abcdef","

O : ","123,456","
R : ","123456","

O : ","abcdef,","
R : ","abcdef,","   <-- we expect the comma after "f" being remove, as 
                        it is inside string quote

我可以知道如何进一步改进这个正则表达式模式吗？

    final Pattern commaNotBetweenQuotes = Pattern.compile("(?<!\"),(?!\")");

我从Different regular expression result in Java SE and Android platform获取代码

我对模式的理解是

If a comma doesn't have double quote on its left AND on its right, replace it with empty string.

我尝试使用

     final Pattern commaNotBetweenQuotes = Pattern.compile("(?<!\"),(?!\")|(?<![\"0-9]),(?=\")");

有想法

If a comma doesn't have double quote on its left AND on its right, replace it with empty string.

OR

If a comma has double quote on its right, and non-digit / non double quote on its left, replace it with empty string.

然而，“解决方案”并不优雅。我真正想要的是，删除字符串文字中的逗号。删除整数中的逗号。保留用作 CSV 分隔符的逗号。

尽量不要使用$1，因为对于不匹配的组，Android 将使用“null”而不是“”。

Answer 1

描述

要替换所有卡在字符串中间的逗号，请使用以下内容，空捕获组 (\b) 应该避免 android 的问题，如果反向引用 $# 不匹配然后语言插入一个空字符而不是什么都不插入:

正则表达式:((?:",\d|\d,")|",")|(\b),

替换为:$1

输入

",123,456," 
","abc,def","
","123,456"," 
","abcdef,","

输出

",123456," 
","abcdef","
","123456"," 
","abcdef","

免责声明

假设您要保留的逗号都被引号包围，例如 "alpha","beta","1234"