Java String Match Count countMatches(final CharSequence str, final CharSequence sub)

Description

Counts how many times the substring appears in the larger string.

License

Open Source License

Parameter

Parameter	Description
str	the CharSequence to check, may be null
sub	the substring to count, may be null

Return

the number of occurrences, 0 if either CharSequence is null

Declaration

public static int countMatches(final CharSequence str, final CharSequence sub) 

Method Source Code

//package com.java2s;
/*/*from   w  ww  .jav a  2 s  . c  om*/
 * Copyright (c) 2006 Stephan D. Cote' - All rights reserved.
 * 
 * This program and the accompanying materials are made available under the 
 * terms of the MIT License which accompanies this distribution, and is 
 * available at http://creativecommons.org/licenses/MIT/
 *
 * Contributors:
 *   Stephan D. Cote 
 *      - Initial concept and implementation
 */

public class Main {
    /**
     * Counts how many times the substring appears in the larger string.
     * 
     * @param str the CharSequence to check, may be null
     * @param sub the substring to count, may be null
     * 
     * @return the number of occurrences, 0 if either CharSequence is {@code null}
     */
    public static int countMatches(final CharSequence str, final CharSequence sub) {
        if (isEmpty(str) || isEmpty(sub)) {
            return 0;
        }
        int count = 0;
        int idx = 0;
        while ((idx = indexOf(str, sub, idx)) != -1) {
            count++;
            idx += sub.length();
        }
        return count;
    }

    /**
     * Checks if a string is null or empty ("").
     * 
     * @param str the String to check, may be null
     * 
     * @return <code>true</code> if the String is empty or null, false otherwise
     * 
     * @see #isNotEmpty(String)
     */
    public static boolean isEmpty(String str) {
        if (str == null || str.length() == 0) {
            return true;
        }
        return false;
    }

    /**
     * @param array
     */
    private static boolean isEmpty(final char[] array) {
        return (array == null) || (array.length == 0);
    }

    /**
     * Checks if a CharSequence is empty ("") or null.
     * 
     * @param cs the CharSequence to check, may be null
     * 
     * @return {@code true} if the CharSequence is empty or null
     */
    public static boolean isEmpty(final CharSequence cs) {
        return (cs == null) || (cs.length() == 0);
    }

    /**
     * Used by the indexOf(CharSequence methods) as a green implementation of indexOf.
     * 
     * @param cs the {@code CharSequence} to be processed
     * @param searchChar the {@code CharSequence} to be searched for
     * @param start the start index
     * 
     * @return the index where the search sequence was found
     */
    private static int indexOf(final CharSequence cs, final CharSequence searchChar, final int start) {
        return cs.toString().indexOf(searchChar.toString(), start);
    }
}

Related

1. countMatches(CharSequence str, CharSequence sub)
2. countMatches(final CharSequence seq, final char c)
3. countMatches(final CharSequence str, final char ch)
4. countMatches(final CharSequence str, final CharSequence sub)
5. countMatches(final CharSequence str, final CharSequence sub)
6. countMatches(final String str, final String sub)
7. countMatches(String line, char chr)
8. countMatches(String reference, String query)