带有捕获组的正则表达式不在Java中工作

Question

我有一些字符串的模式如下：

• PSHELF-2[PSHELF-MF-6RU]
• 货架-5[货架M6]
• 货架-6[货架M15]
• 货架-6[货架M15]

我想突出显示信息
为此，我使用以下正则表达式：

(.*SHELF)-(.*)\[.*SHELF-(.*)\]

我用regex101测试了它

如果我尝试在Java上实现相同的登录

Pattern pattern = Pattern.compile("(.*SHELF)-(.*)\\[.*SHELF-(.*)\\]");
Matcher matcher = pattern.matcher(inputString);
String group1 = matcher.group(1);
String group2 = matcher.group(2);
String group3 = matcher.group(3);

我得到了以下错误：

java.lang.IllegalStateException: No match found

为什么

Answer 1

This post回答了你最初的问题

---

This expression创建捕获组并以多种形式返回所需的输出：

(([A-Z]+)-([0-9]+))\[([A-Z]+)-([A-Z0-9-]+)(\])

如果你愿意的话，你可以进一步简化它

Java测试

import java.util.regex.Matcher;
import java.util.regex.Pattern;

final String regex = "(([A-Z]+)-([0-9]+))\\[([A-Z]+)-([A-Z0-9-]+)(\\])";
final String string = "PSHELF-2[PSHELF-MF-6RU]\n"
     + "SHELF-5[SHELF-M6]\n"
     + "SHELF-6[SHELF-M15]\n"
     + "SHELF-6[SHELF-M15]";
final String subst = "\\1 \\4";

final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
final Matcher matcher = pattern.matcher(string);

// The substituted value will be contained in the result variable
final String result = matcher.replaceAll(subst);

System.out.println("Substitution result: " + result);

JavaScript演示

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const regex = /(([A-Z]+)-([0-9]+))\[([A-Z]+)-([A-Z0-9-]+)(\])/gm;
const str = `PSHELF-2[PSHELF-MF-6RU]
SHELF-5[SHELF-M6]
SHELF-6[SHELF-M15]
SHELF-6[SHELF-M15]`;
const subst = `\nGroup 1: $1\nGroup 2: $2\nGroup3: $3\nGroup 4: $4\nGroup 5: $5`;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log('Substitution result: ', result);

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正则表达式描述图

此图显示了表达式的工作方式，您可以在link中可视化其他表达式：

基本性能测试

这个JavaScript片段使用一个简单的100万次for循环来显示表达式的性能

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const repeat = 1000000;
const start = Date.now();

for (var i = repeat; i >= 0; i ) {
	const string = 'PSHELF-2[PSHELF-MF-6RU]';
	const regex = /(([A-Z]+)-([0-9]+))\[([A-Z]+)-([A-Z0-9-]+)(\])/gm;
	var match = string.replace(regex, "\nGroup #1: $1\nGroup #2: $2 \nGroup #3: $3 \nGroup #4: $4\nGroup #5: $5\n");
}

const end = Date.now() - start;
console.log("YAAAY! \"" + match + "\" is a match 💚💚💚 ");
console.log(end / 1000 + " is the runtime of " + repeat + " times benchmark test. 😳 ");

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