Java String match from start

//package com.demo2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        String str = "demo2s.com";
        String prefix = "demo";
        System.out.println(startsWith(str, prefix));
    }//from   w  w w  . j  a  va 2 s  .co  m

    /**
     * <p>Check if a String starts with a specified prefix.</p>
     *
     * <p><code>null</code>s are handled without exceptions. Two <code>null</code>
     * references are considered to be equal. The comparison is case sensitive.</p>
     *
     * <pre>
     * startsWith(null, null)      = true
     * startsWith(null, "abcdef")  = false
     * startsWith("abc", null)     = false
     * startsWith("abc", "abcdef") = true
     * startsWith("abc", "ABCDEF") = false
     * </pre>
     *
     * @see java.lang.String#startsWith(String)
     * @param str  the String to check, may be null
     * @param prefix the prefix to find, may be null
     * @return <code>true</code> if the String starts with the prefix, case sensitive, or
     *  both <code>null</code>
     * @since 2.4
     */
    public static boolean startsWith(String str, String prefix) {
        return startsWith(str, prefix, false);
    }

    /**
     * <p>Check if a String starts with a specified prefix (optionally case insensitive).</p>
     *
     * @see java.lang.String#startsWith(String)
     * @param str  the String to check, may be null
     * @param prefix the prefix to find, may be null
     * @param ignoreCase inidicates whether the compare should ignore case
     *  (case insensitive) or not.
     * @return <code>true</code> if the String starts with the prefix or
     *  both <code>null</code>
     */
    private static boolean startsWith(String str, String prefix, boolean ignoreCase) {
        if (str == null || prefix == null) {
            return (str == null && prefix == null);
        }
        if (prefix.length() > str.length()) {
            return false;
        }
        return str.regionMatches(ignoreCase, 0, prefix, 0, prefix.length());
    }

}

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */