Here you can find the source of countMatches(String str, String sub)
Counts how many times the substring appears in the larger String.
A null
or empty ("") String input returns 0
.
StringUtils.countMatches(null, *) = 0 StringUtils.countMatches("", *) = 0 StringUtils.countMatches("abba", null) = 0 StringUtils.countMatches("abba", "") = 0 StringUtils.countMatches("abba", "a") = 2 StringUtils.countMatches("abba", "ab") = 1 StringUtils.countMatches("abba", "xxx") = 0
Parameter | Description |
---|---|
str | the String to check, may be null |
sub | the substring to count, may be null |
null
public static int countMatches(String str, String sub)
//package com.java2s; public class Main { /**//from ww w . j ava 2 s . c o m * <p>Counts how many times the substring appears in the larger String.</p> * * <p>A <code>null</code> or empty ("") String input returns <code>0</code>.</p> * * <pre> * StringUtils.countMatches(null, *) = 0 * StringUtils.countMatches("", *) = 0 * StringUtils.countMatches("abba", null) = 0 * StringUtils.countMatches("abba", "") = 0 * StringUtils.countMatches("abba", "a") = 2 * StringUtils.countMatches("abba", "ab") = 1 * StringUtils.countMatches("abba", "xxx") = 0 * </pre> * * @param str the String to check, may be null * @param sub the substring to count, may be null * @return the number of occurrences, 0 if either String is <code>null</code> */ public static int countMatches(String str, String sub) { if (isEmpty(str) || isEmpty(sub)) { return 0; } int count = 0; int idx = 0; while ((idx = str.indexOf(sub, idx)) != -1) { count++; idx += sub.length(); } return count; } /** * <p>Checks if a String is empty ("") or null.</p> * * <pre> * StringUtils.isEmpty(null) = true * StringUtils.isEmpty("") = true * StringUtils.isEmpty(" ") = false * StringUtils.isEmpty("bob") = false * StringUtils.isEmpty(" bob ") = false * </pre> * * <p>NOTE: This method changed in Lang version 2.0. * It no longer trims the String. * That functionality is available in isBlank().</p> * * @param str the String to check, may be null * @return <code>true</code> if the String is empty or null */ public static boolean isEmpty(String str) { return str == null || str.length() == 0; } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(int)}.</p> * * <p>A <code>null</code> or empty ("") String will return <code>-1</code>.</p> * * <pre> * StringUtils.indexOf(null, *) = -1 * StringUtils.indexOf("", *) = -1 * StringUtils.indexOf("aabaabaa", 'a') = 0 * StringUtils.indexOf("aabaabaa", 'b') = 2 * </pre> * * @param str the String to check, may be null * @param searchChar the character to find * @return the first index of the search character, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, char searchChar) { if (isEmpty(str)) { return -1; } return str.indexOf(searchChar); } /** * <p>Finds the first index within a String from a start position, * handling <code>null</code>. * This method uses {@link String#indexOf(int, int)}.</p> * * <p>A <code>null</code> or empty ("") String will return <code>-1</code>. * A negative start position is treated as zero. * A start position greater than the string length returns <code>-1</code>.</p> * * <pre> * StringUtils.indexOf(null, *, *) = -1 * StringUtils.indexOf("", *, *) = -1 * StringUtils.indexOf("aabaabaa", 'b', 0) = 2 * StringUtils.indexOf("aabaabaa", 'b', 3) = 5 * StringUtils.indexOf("aabaabaa", 'b', 9) = -1 * StringUtils.indexOf("aabaabaa", 'b', -1) = 2 * </pre> * * @param str the String to check, may be null * @param searchChar the character to find * @param startPos the start position, negative treated as zero * @return the first index of the search character, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, char searchChar, int startPos) { if (isEmpty(str)) { return -1; } return str.indexOf(searchChar, startPos); } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(String)}.</p> * * <p>A <code>null</code> String will return <code>-1</code>.</p> * * <pre> * StringUtils.indexOf(null, *) = -1 * StringUtils.indexOf(*, null) = -1 * StringUtils.indexOf("", "") = 0 * StringUtils.indexOf("aabaabaa", "a") = 0 * StringUtils.indexOf("aabaabaa", "b") = 2 * StringUtils.indexOf("aabaabaa", "ab") = 1 * StringUtils.indexOf("aabaabaa", "") = 0 * </pre> * * @param str the String to check, may be null * @param searchStr the String to find, may be null * @return the first index of the search String, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, String searchStr) { if (str == null || searchStr == null) { return -1; } return str.indexOf(searchStr); } }