Question

我有一个输入，在$和值之间有一个空格，我想删除空格。这段代码：

System.out.println("This costs $ 5 even.".replaceAll("\\$ ", "$"));

应打印出来：

This costs $5 even.

但它引发了一个例外：

Illegal group reference: group index is missing
java.lang.IllegalArgumentException
    at java.util.regex.Matcher.appendReplacement(Matcher.java:819)
    at java.util.regex.Matcher.replaceAll(Matcher.java:955)
    at java.lang.String.replaceAll(String.java:2223)
    at DollarTest.test(DollarTest.java:18)

我错过了什么？

Answer 1

只需使用replace()：

System.out.println("This costs $ 5 even.".replace("$ ", "$"));

Answer 2

问题是在正则表达式替换字符串中，$是特殊的。它应该用于指代正则表达式本身的捕获组。

你需要逃脱它：

.replaceAll("\\$ ", "\\$")

但是as @pp_ mentions，你最好在这里使用普通的.replace()。

Answer 3

另一种选择 - 在空格周围对$和值进行分组，然后在替换中将它们连接起来。

String s = "This costs $ 5 even. That costs $ 6 even. This is a $ sign.";
System.out.println(s.replaceAll("(\\$)\\s(\\d+)", "$1$2"));

输出

This costs $5 even. That costs $6 even. This is a $ sign.

它还指出了其他答案中的缺陷

String s = "This costs $ 5 even. That costs $ 6 even. This is a $ sign.";
System.out.println(s.replaceAll("\\$ ", "\\$"));

输出"$sign"。

This costs $5 even. That costs $6 even. This is a $sign.

Answer 4

我建议您使用以下正则表达式删除$和下一个数字之间的任意数量的空格。

try {
    String data = "This costs $          7 even";
    String resultString = data.replaceAll("(?is)(?<=\\$)\\s*(?=\\d+)", "");
    System.out.println(resultString);

} catch (PatternSyntaxException ex) {

}

输入：

This costs $ 5 even
This costs $6 even
This costs $          7 even
This costs $          77 even
This costs $          7.2 even
This costs $          0.21 even
It's cost is between $   5.2 and $   8.3
You don't have to pay top $ for this.

输出：

This costs $5 even
This costs $6 even
This costs $7 even
This costs $77 even
This costs $7.2 even
This costs $0.21 even
It's cost is between $5.2 and $8.3
You don't have to pay top $ for this.

如何在字符串中的$后删除空格？

4 个答案: