Java - Write code to Return the given string with the first letter converted to lower case.

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Requirements

Write code to Return the given string with the first letter converted to lower case.

Demo

/*
 * Copyright (c) 2001-2002, Marco Hunsicker. All rights reserved.
 *
 * This software is distributable under the BSD license. See the terms of the
 * BSD license in the documentation provided with this software.
 *//*  www .  j  av a  2  s  .  c o m*/
 
//package com.book2s;

public class Main {
    public static void main(String[] argv) {
        String str = "This is book2s.com";
        System.out.println(lowercaseFirst(str));
    }

    /**
     * Returns the given string with the first letter converted to lower case.
     *
     * @param str string to transform.
     *
     * @return the transformed string. If the string already begins with a lower case
     *         letter or is the empty string, the original string is returned.
     */
    public static String lowercaseFirst(String str) {
        if (str.length() == 0) {
            return str;
        }

        if (isUppercase(str.charAt(0))) {
            char[] letters = str.toCharArray();
            letters[0] = (char) (letters[0] + 32);

            return new String(letters);
        }

        return str;
    }

    /**
     * Returns <code>true</code> if the given letter is uppercase.
     *
     * @param letter letter to check for capitalization.
     *
     * @return <code>true</code> if the given letter is uppercase.
     */
    public static boolean isUppercase(char letter) {
        if ((letter < 'A') || (letter > 'Z')) {
            return false;
        }

        return true;
    }
}

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