问题

我需要文本字段中括号内的注释值。示例：

```java
String text = "I have simple annotation @Test(value123) and ..";

我可以找到带有值的注释本身，但我不明白如何在没有注释的情况下获取它。

Pattern patternString = Pattern.compile("@Test\\(\\s+\\)");

结果：

>@Test(value123)

但我需要

>value123

<details>
<summary>英文:</summary>

I need the value in parentheses for the annotation in the text field. Example:

```String text = &quot;I have simple annotation @Test(value123) and ..```

I can find the annotation itself with a value, but I don&#39;t understand how to get it without an annotation
```Pattern patternString = Pattern.compile(&quot;@Test\\(\\s+\\)&quot;);```

Result: 

&gt;@Test(value123)

but I need 

&gt;value123


</details>


# 答案1
**得分**: 2

添加一个（X）[捕获组][1]：

```lang-java
String text = "I have simple annotation @Test(value123) and ..";
Pattern p = Pattern.compile("@Test\\(([^)]*)\\)");
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group(1)); // 打印捕获组 1
}

输出

value123

解释

@Test\(     匹配 '@Test('
(           开始捕获组 1
  [^)]*       匹配零个或多个字符，不包括')'
)           结束捕获组 1
\)          匹配 ')'

或者，使用 (?<=X) 零宽度正回顾后发断言 和 (?=X) 零宽度正先行断言：

String text = "I have simple annotation @Test(value123) and ..";
Pattern p = Pattern.compile("(?<=@Test\\()[^)]*(?=\\))");
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group()); // 打印匹配的文本
}

输出

value123

解释

(?<=          开始零宽度正回顾后发断言
  @Test\(       匹配 '@Test('
)             结束零宽度正回顾后发断言
[^)]*         匹配零个或多个字符，不包括')'
(?=           开始零宽度正先行断言
  \)            匹配 ')'
)             结束零宽度正先行断言

String text = "I have simple annotation @Test(value123) and ..";
Pattern p = Pattern.compile("@Test\\(([^)]*)\\)");
Matcher m = p.matcher(text);
if (m.find()) {
	System.out.println(m.group(1)); // Print capture group 1
}

value123

@Test\(     Match '@Test('
(           Start of capturing group 1
  [^)]*       Match zero-or-more characters, except ')'
)           End of capturing group 1
\)          Match ')'

String text = "I have simple annotation @Test(value123) and ..";
Pattern p = Pattern.compile("(?<=@Test\\()[^)]*(?=\\))");
Matcher m = p.matcher(text);
if (m.find()) {
	System.out.println(m.group()); // Print matched text
}

value123

(?<=          Start of zero-width positive lookbehind
  @Test\(       Match '@Test('
)             End of zero-width positive lookbehind
[^)]*         Match zero-or-more characters, except ')'
(?=           Start of zero-width positive lookahead
  \)            Match ')'
)             End of zero-width positive lookahead

答案2

得分: 0

你可以使用一个匹配器，就像这样：

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

class Main {
  public static void main(String[] args) {
    String testString = "@Test(value123)";
    // 未转义的括号捕获组
    // 注意我将 \\s+ 更改为 .+，
    // 因为我想匹配括号内的任何内容，
    // 而不是空格（但是，您应根据自己的需求进行调整）
    Pattern pattern = Pattern.compile("@Test\\((.+)\\)");
    Matcher matcher = pattern.matcher(testString);
    if (matcher.matches()) {
      String value = matcher.group(1);
      System.out.println(value); // 输出 value123
    }
  }
}

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

class Main {
  public static void main(String[] args) {
    String testString = "@Test(value123)";
    // unescaped parentheses catch the group
    // note that I changed \\s+ to .+,
    // since I want to match whatever is inside the parentheses,
    // not whitespaces (however, you should adjust it to your needs)
    Pattern pattern = Pattern.compile("@Test\\((.+)\\)");
    Matcher matcher = pattern.matcher(testString);
    if (matcher.matches()) {
      String value = matcher.group(1);
      System.out.println(value); // prints value123
    }
  }
}