java正则表达式示例

以下是一些Java正则表达式的示例：

匹配数字：

String pattern = "\\d+";
String text = "The price is $25.99";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
while (m.find()) {
    System.out.println(m.group());
}

输出：25, 99

匹配邮箱：

String pattern = "\\w+@\\w+\\.\\w+";
String text = "My email is john@example.com";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group());
}

输出：john@example.com

匹配电话号码：

String pattern = "\\d{3}-\\d{3}-\\d{4}";
String text = "My phone number is 555-123-4567";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group());
}

输出：555-123-4567

匹配日期：

String pattern = "\\d{4}-\\d{2}-\\d{2}";
String text = "The date is 2023-05-09";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group());
}

输出：2023-05-09

这些只是一些简单的示例，正则表达式在Java中的应用非常广泛，可以用于字符串匹配、替换、分割等操作。

匹配URL：

String pattern = "^(http|https)://[\\w\\-]+(\\.[\\w\\-]+)+([\\w\\-.,@?^=%&:/~+#]*[\\w\\-@?^=%&/~+#])?$";
String text = "Visit my website at https://www.example.com";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group());
}

输出：https://www.example.com

匹配IP地址：

String pattern = "^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\." +
                 "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\." +
                 "([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\." +
                 "([01]?\\d\\d?|2[0-4]\\d|25[0-5])$";
String text = "My IP address is 192.168.1.1";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group());
}

输出：192.168.1.1

匹配中文字符：

String pattern = "[\u4e00-\u9fa5]";
String text = "中文字符";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
while (m.find()) {
    System.out.println(m.group());
}

输出：中, 文, 字, 符

替换字符串：

String pattern = "\\bcat\\b";
String text = "I have a cat and a caterpillar";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
String replacedText = m.replaceAll("dog");
System.out.println(replacedText);

输出：I have a dog and a caterpillar

这些示例演示了如何使用Java的正则表达式来匹配不同类型的文本模式。当然，正则表达式可以更加复杂，而这里提供的仅仅是一些入门示例。

匹配HTML标签：

String pattern = "<(\"[^\"]*\"|'[^']*'|[^'\">])*>";
String text = "<p>Example HTML code</p>";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.find()) {
    System.out.println(m.group());
}

输出：<p>Example HTML code</p>

匹配多个空格：

String pattern = "\\s+";
String text = "Multiple   spaces    between   words.";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
String replacedText = m.replaceAll(" ");
System.out.println(replacedText);

输出：Multiple spaces between words.

分割字符串：

String pattern = "\\s+";
String text = "Split this sentence into words.";
String[] words = text.split(pattern);
for (String word : words) {
    System.out.println(word);
}

输出：Split, this, sentence, into, words.

捕获分组：

String pattern = "(\\d{4})-(\\d{2})-(\\d{2})";
String text = "The date is 2023-05-09";
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(text);
if (m.find()) {
    String year = m.group(1);
    String month = m.group(2);
    String day = m.group(3);
    System.out.println("Year: " + year);
    System.out.println("Month: " + month);
    System.out.println("Day: " + day);
}

输出：Year: 2023, Month: 05, Day: 09

以上这些示例展示了Java正则表达式的更多应用，包括匹配HTML标签、捕获分组等。正则表达式可以应用于许多不同的场景中，具有很大的灵活性和适应性。

原文链接：codingdict.net

java正则表达式示例

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