// PalindromeChecker.java

public class PalindromeChecker
{
	private String testString; // user entered string

	// constructor
	public PalindromeChecker()
	{
		testString = "";
	} // end constructor


	// set testString
	public void settestString( String str )
	{
		testString =  str;
	} // end method settestString


	// get testString
	public String gettestString()
	{
		return testString;
	} // end method gettestString


	public String parseString()
	{
		String str = gettestString();
		String newStr = ""; // string after all extraneous characters removed
		int length; // length of string
		char tempChar = ' '; // individual characters of the string

		for ( int i = 0; i <= str.length() - 1; i++ )
		{
			tempChar = str.charAt( i );
			if ( Character.isLetterOrDigit( tempChar ) ) // append letter or digit to newStr
				newStr += tempChar;
		} // end for

		return newStr;
	} // end method inputString


	// recursive method
	public boolean testPalindrome( String string )
	{
		String str = string;
		String newStr;

		// ignores case of character in string e.g. a = A
		Character begChar = Character.toLowerCase( str.charAt( 0 ) );
		Character endChar = Character.toLowerCase( str.charAt( str.length() - 1 ) );

		// base case: length of string <= 1
		if ( str.length() <= 1 )
		{
			return true;
		}
		else if ( begChar.equals( endChar ) )
			{
				if( str.length() == 2 )
					return true;
				else
				{
					newStr = str.substring( 1, str.length() - 1 ); // shorten the string
					return testPalindrome( newStr ); // recursive call with shortened string
				}
			} // end if
		else
			{
				return false; // if 1st and last characters are different
			}
	} // end method testPalindrome
} // end class