Java字符串匹配：Pattern与Matcher类介绍

Pattern pattern = Pattern.compile("a*b");

Matcher matcher = pattern.matcher("aaaaab");

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5while (matcher.find()) {
    System.out.println("Found match at: " + matcher.start() + " - " + matcher.end());
    System.out.println("Matched substring: " + matcher.group());
}

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8String input = "Emails: example1@email.com, example2@email.com";
Pattern emailPattern = Pattern.compile("\\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Z|a-z]{2,}\\b");
Matcher emailMatcher = emailPattern.matcher(input);

while (emailMatcher.find()) {
    System.out.println("Found email: " + emailMatcher.group());
}

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7String input = "The cat and the hat";
Pattern pattern = Pattern.compile("\\b cat \\b");
Matcher matcher = pattern.matcher(input);
String replacedString = matcher.replaceAll("dog");

System.out.println("Replaced string: " + replacedString);

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26// 正则表达式匹配数字和运算符
			String regex = "([\\d.]+)\\s*([-+*/])\\s*([\\d.]+)";
			Pattern pattern = Pattern.compile(regex);
			Matcher matcher = pattern.matcher(expression);
			if(matcher.find())
			{
				double operand1 = Double.parseDouble(matcher.group(1));
				String operator = matcher.group(2);
				double operand2 = Double.parseDouble(matcher.group(3));
				// 根据运算符计算结果
				switch(operator)
				{
					case "+":
						return operand1 + operand2;
					case "-":
						return operand1 - operand2;
					case "*":
						return operand1 * operand2;
					case "/":
						return operand1 / operand2;
					default:
						// 处理其他运算符
						break;
				}
            }

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10Pattern pattern = Pattern.compile("(\\d{3})-(\\d{3})-(\\d{4})");
Matcher matcher = pattern.matcher("Phone numbers: 123-456-7890, 987-654-3210");

while (matcher.find()) {
    System.out.println("Full match: " + matcher.group(0));
    System.out.println("Area code: " + matcher.group(1));
    System.out.println("Prefix: " + matcher.group(2));
    System.out.println("Suffix: " + matcher.group(3));
}

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15String text = "aaaaaa";
Pattern greedyPattern = Pattern.compile("a+");
Pattern reluctantPattern = Pattern.compile("a+?");

Matcher greedyMatcher = greedyPattern.matcher(text);
Matcher reluctantMatcher = reluctantPattern.matcher(text);

while (greedyMatcher.find()) {
    System.out.println("Greedy match: " + greedyMatcher.group());
}

while (reluctantMatcher.find()) {
    System.out.println("Reluctant match: " + reluctantMatcher.group());
}

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9Pattern pattern = Pattern.compile("(?<year>\\d{4})-(?<month>\\d{2})-(?<day>\\d{2})");
Matcher matcher = pattern.matcher("Date: 2023-11-22");

while (matcher.find()) {
    System.out.println("Year: " + matcher.group("year"));
    System.out.println("Month: " + matcher.group("month"));
    System.out.println("Day: " + matcher.group("day"));
}

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10String password = "Passw0rd!";
Pattern pattern = Pattern.compile("^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%^&+=!])(?=\\S+$).{8,}$");
Matcher matcher = pattern.matcher(password);

if (matcher.matches()) {
    System.out.println("Strong password!");
} else {
    System.out.println("Weak password!");
}