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Java 计算正则表达式出现在较大的String中的次数。

欢马劈雪

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计算正则表达式出现在较大的String中的次数。

实例源码：

源代码：

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/**

* This class is based, in part, on org.apache.commons.lang.StringUtils and is intended

* to break the dependency on that project.

* @author <a href="http://jakarta.apache.org/turbine/">Apache Jakarta Turbine</a>

* @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>

* @author Daniel L. Rall

* @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a>

* @author <a href="mailto:ed@apache.org">Ed Korthof</a>

* @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a>

* @author Stephen Colebourne

* @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>

* @author Holger Krauth

* @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a>

* @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>

* @author Arun Mammen Thomas

* @author Gary Gregory

* @author Phil Steitz

* @author Al Chou

* @author Michael Davey

* @author Reuben Sivan

* @author Chris Hyzer

*  Johnson

*/
 /*
 来 自*
  n o w j a v a . c o m - 时代Java
 */

//package com.nowjava;

import java.util.regex.Pattern;

import java.util.regex.Matcher;

public class Main {

public static void main(String[] argv) {

String str = "nowjava.com";

String regexp = "nowjava.com";

System.out.println(countRegexpMatches(str, regexp));

}

/**

* Counts how many times the regexp appears in the larger String.

* A <code>null</code> or empty ("") String input returns <code>0</code>.

* <pre>

* countMatches(null, *)       = 0

* countMatches("", *)         = 0

* countMatches("abba", null)  = 0

* countMatches("abba", "")    = 0

* countMatches("abba", "a")   = 2

* countMatches("abba", "ab")  = 1

* countMatches("abba", ".b")  = 2

* countMatches("abba", "xxx") = 0

* </pre>

* @param str  the String to check, may be null

* @param regexp  the regexp to count, may be null

* @return the number of occurrences, 0 if either String is <code>null</code>

public static int countRegexpMatches(String str, String regexp) {

if (isEmpty(str) || isEmpty(regexp)) {

return 0;

}//from 时 代      J a v a   公   众 号 - nowjava.com

Pattern pattern = Pattern.compile(regexp);

Matcher matcher = pattern.matcher(str);

int i = 0;

while (matcher.find()) {

i++;

}

return i;

}

/**

* Checks if a String is empty ("") or null.

* <pre>

* StringUtils.isEmpty(null)      = true

* StringUtils.isEmpty("")        = true

* StringUtils.isEmpty(" ")       = false

* StringUtils.isEmpty("bob")     = false

* StringUtils.isEmpty("  bob  ") = false

* </pre>

* NOTE: This method changed in Lang version 2.0.

* It no longer trims the String.

* That functionality is available in isBlank().

* @param str  the String to check, may be null
/**代码未完, 请加载全部代码(NowJava.com).**/

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编辑于 2020-03-26 09:23:272020-03-26 09:23:27

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