BasicStringManipulation

/* StringManipulate
 * <Description>
 * Various string manipulation methods.
 *
 * <Usage>
 * %javac StringManipulate.java
 * %java String Manipulate Butties
 * 1
 * BUTTIES
 * seittuB
 *
 * %java StringManipulate 1 Butties.jpg
 * .jpg
 *
 * <References>
 * CIS-201L Dr. Sloan Lab 8
 * @author
 * Dan Latham
 * <[email protected]>
 * @version 0.0.1
 *
 */
public class StringManipulate
{
    //Returns occurence of letter e in string
    public static int occurrence(String string)
    {
        int count = 0;
        int leng = string.length();
        char[] str = new char[leng];
        string.getChars(0,leng, str, 0);
        for (int i = 0; i < leng; i+=1)
        {
            if (str[i] == 'e') count+=1;
        }
        return count;
    }
    //Returns string as STRING
    public static String upper(String string)
    {
        return string.toUpperCase();
    }
    //Returns string as gnirts
    public static String reverse(String string)
    {
        int leng = string.length();
        int counter = 0;
        char[] str = new char[leng];
        char[] str_new = new char[leng];
        string.getChars(0,leng, str, 0);
        for (int i = leng-1; i >= 0; i-=1)
        {
            str_new[counter] = str[i];
            counter+=1;
        }
        String basic = "";
        for (int i = 0; i < leng; i +=1)
        {
            basic += str_new[i];
        }
        return basic;
    }
    //Returns file ext of file.jpg as .jpg
    public static String filext(String string)
    {
        int leng = string.length();
        char[] str = new char[leng];
        String stringext = "";
        string.getChars(0,leng, str, 0);
        int i = leng-1;
        while (i >= 0)
        {
            stringext += str[i];
            //System.out.println(stringext);
            if (str[i] == '.')
            {
                i = -1;
                return reverse(stringext);
            }
            i -= 1;
        }

        return "No File Extension Found in Filename";
    }
    public static void main(String[] args)
    {
        try
        {
            Integer.parseInt(args[0]);
            String c = args[1];
            System.out.println(filext(c));
        }
        catch (NumberFormatException j)
        {
            System.out.println(occurrence(args[0]));
            System.out.println(upper(args[0]));
            System.out.println(reverse(args[0]));
        }
    }
}