Java String Index Of indexOfIgnoreCase(String str, String substring)

Description

Helper method to obtain the starting index of a substring within another string, ignoring their case.

License

Open Source License

Parameter

Parameter	Description
str	the string in which to search for the <tt>substring</tt> argument
substring	the substring to search for in <tt>str</tt>

Return

if the substring argument occurs as a substring within str, then the index of the first character of the first such substring is returned; if it does not occur as a substring, -1 is returned

Declaration

public static int indexOfIgnoreCase(String str, String substring)

Method Source Code

//package com.java2s;
/*/*from  w  ww.  j  av a2s  .  co  m*/
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.*;

public class Main {
    /**
     * Helper method to obtain the starting index of a substring within another
     * string, ignoring their case.  This method is expensive because it has
     * to set each character of each string to lower case before doing the
     * comparison.  Uses the default <code>Locale</code> for case conversion.
     *
     * @param str the string in which to search for the <tt>substring</tt>
     *  argument
     * @param substring the substring to search for in <tt>str</tt>
     * @return if the <tt>substring</tt> argument occurs as a substring within
     *  <tt>str</tt>, then the index of the first character of the first such
     *  substring is returned; if it does not occur as a substring, -1 is
     *  returned
     */
    public static int indexOfIgnoreCase(String str, String substring) {
        return indexOfIgnoreCase(str, substring, Locale.getDefault());
    }

    /**
     * Helper method to obtain the starting index of a substring within another
     * string, ignoring their case.  This method is expensive because it has
     * to set each character of each string to lower case before doing the
     * comparison.
     *
     * @param str the string in which to search for the <tt>substring</tt>
     *  argument
     * @param substring the substring to search for in <tt>str</tt>
     * @param locale the <code>Locale</code> to use when converting the
     *  case of <code>str</code> and <code>substring</code>.  This is necessary because
     *  case conversion is <code>Locale</code> specific.
     * @return if the <tt>substring</tt> argument occurs as a substring within
     *  <tt>str</tt>, then the index of the first character of the first such
     *  substring is returned; if it does not occur as a substring, -1 is
     *  returned
     */
    public static int indexOfIgnoreCase(String str, String substring, Locale locale) {
        // Look for the index after the expensive conversion to lower case.
        return str.toLowerCase(locale).indexOf(substring.toLowerCase(locale));
    }
}