Java - 字符串替换确切的单词
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Java - String replace exact word
提问by Oti Na Nai
String x = "axe pickaxe";
x = x.replace("axe", "sword");
System.out.print(x);
By this code, I am trying to replace the exact word axewith sword. However, if I run this, it prints sword pickswordwhile I would like to print sword pickaxeonly, as pickaxeis a different word from axealthough it contains it. How can I fix this? Thanks
通过这段代码，我试图axe用sword. 但是，如果我运行它，它sword picksword会在我只想打印时打印sword pickaxe，虽然它包含它pickaxe，axe但它是一个不同的词。我怎样才能解决这个问题？谢谢
采纳答案by hiergiltdiestfu
Use a regex with word boundaries\b:
使用带有字边界的正则表达式\b：
String s = "axe pickaxe";
System.out.println(s.replaceAll("\baxe\b", "sword"));
The backslash from the boundary symbol must be escaped, hence the double-backslashes.
边界符号的反斜杠必须被转义，因此是双反斜杠。
回答by SubOptimal
Include the word boundary before and after the word you want to replace.
在要替换的单词前后包括单词边界。
String x = "axe pickaxe axe";
x = x.replaceAll("\baxe\b", "sword");
System.out.print(x);
editoutput
编辑输出
sword pickaxe sword
回答by Steve Chaloner
You can use \bto define the word boundary, so \baxe\bin this case.
您可以使用\b来定义单词边界，因此\baxe\b在这种情况下。
x = x.replaceAll("\baxe\b");
回答by Veselin Davidov
System.out.println("axe pickaxe".replaceAll("\baxe\b", "sword"));
You need to use replaceAll instead of replace - because it can work with regular expressions. Then use the meta character \b which is for word boundary. In order to use it you need to escape the \ as double \ so the reges become \\baxe\\b
您需要使用 replaceAll 而不是 replace - 因为它可以使用正则表达式。然后使用元字符 \b 用于单词边界。为了使用它，你需要将 \ 转义为双 \ 所以reges 变成\\baxe\\b
回答by Avinash Raj
Some other answers suggest you to use \\bword boundaries to match an exact word. But \\bfoo\\bwould match the substring fooin .foo.. If you don't want this type of behavior then you may consider using lookaround based regex.
其他一些答案建议您使用\\b单词边界来匹配精确的单词。但是，\\bfoo\\b将匹配子foo在.foo.。如果您不想要这种类型的行为，那么您可以考虑使用基于环视的正则表达式。
System.out.println(string.replaceAll("(?<!\S)axe(?!\S)", "sword"));
Explanation:
解释：
(?<!\\S)Negative lookbehind which asserts that the match won't be preceded by a non-space character. i.e. the match must be preceded by start of the line boundary or a space.(?!\\S)Negative lookahead which asserts that the match won't be followed by a non-space character, i.e. the match must be followed by end of the line boundary or space. We can't use(?<=^|\\s)axe(?=\\s|$)since Java doesn't support variable length lookbehind assertions.
(?<!\\S)否定的lookbehind 断言匹配不会以非空格字符开头。即匹配必须以行边界或空格的开头开头。(?!\\S)否定前瞻，断言匹配后不会跟随非空格字符，即匹配后必须是行边界或空格的结尾。我们不能使用，(?<=^|\\s)axe(?=\\s|$)因为 Java 不支持可变长度的后视断言。
回答by Alvin Magalona
If you only want to replace the first occurrence, there is a method replaceFirstin Stringobject.
如果你只想要替换第一次出现，是有方法replaceFirst的String对象。
String x = "axe pickaxe";
x = x.replaceFirst("axe", "sword");
System.out.print(x); //returns sword pickaxe
