Java字符串替换'&'与& amp; amp;但不是& amp;到& amp; amp; [英] Java String Replace '&' with & but not & to &

问题描述

我有一个大字符串，我有&以下模式中使用的字符 -

I have a large String in which I have & characters used available in following patterns -

A&B
A & B
A& B
A &B
A&B
A & B
A& B
A &B

我想要替换所有出现的&字符到& amp;
在替换它时，我还需要确保我不会错误地转换& amp; 至& amp; amp; 。我如何以精通业绩的方式做到这一点？我使用正则表达式吗？如果是的话，请你能帮助我选择正确的正则表达式吗？

I want to replace all the occurrences of & character to & While replacing this, I also need to make sure that I do not mistakenly convert an & to &. How do I do that in a performance savvy way? Do I use regular expression? If yes, please can you help me to pickup the right regular expression to do the above?

到目前为止，我一直试着追随并不高兴：

I've tried following so far with no joy:

data = data.replace(" & ", "&"); // doesn't replace all &
data = data.replace("&", "&");   // replaces all &, so & becomes &

推荐答案

您可以将正则表达式与一起使用否定预测。

You can use a regular expression with a negative lookahead.

正则表达式字符串将是&（？！amp;）。

The regex string would be &(?!amp;).

使用 replaceAll ，你会得到：

A&B
A & B
A& B
A &B
A&B
A & B
A& B
A &B

所以单个字符串的代码 str 将是：

So the code for a single string str would be:

str.replaceAll("&(?!amp;)", "&");

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