palindromes.java

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import java.text.Normalizer;
import java.util.regex.Pattern;
 
public class palindromes {
 
     public static boolean isPalindrome (String s) { 
            int i, j;
            s = s.toUpperCase();
            for (i = 0, j = s.length()-1; i < j; i++, j--) {
                 if (s.charAt(i) != s.charAt(j))
                     return false;
            }
            return true;
     }
 
     public static String reverse (String s) { 
            int i, j;
            StringBuilder str = new StringBuilder(s);
            for (i = 0, j = s.length()-1; i < j; i++, j--) {
                 str.setCharAt(i, s.charAt(j));
                 str.setCharAt(j, s.charAt(i));
            }
            return str.toString();
     }
 
     public static String revString (String str) {
            if (str.length() == 0) 
                return str;
            return revString(str.substring(1)) + str.charAt(0);
     }
 
     public static String reverseWords (String s) { 
            StringBuffer str = new StringBuffer();
            for (String part : s.split(" ")) {
                 str.append (new StringBuffer(part).reverse()+" ");
            }
            return str.toString();
     }
 
     public static String deAccent(String str) {
            String nfdNormalizedString = Normalizer.normalize(str, Normalizer.Form.NFD); 
            Pattern pattern = Pattern.compile("\\p{InCombiningDiacriticalMarks}+");
            return pattern.matcher(nfdNormalizedString).replaceAll("");
     }
 
     public static String removeSpacesAndPonctuation (String s) {
            StringBuffer s1 = new StringBuffer();
            String unWantedChars = " -,:;._'!";
            for ( int i = 0; i < s.length(); ++i ) {
                  char c = s.charAt(i);
                  if ( unWantedChars.indexOf(c) < 0 )  // remove spaces and punctuation
                       s1.append (Character.toUpperCase(c));
            }
            return s1.toString();
     }
 
     public static boolean areAnagrams (String s1, String s2) {
            s1 = deAccent (removeSpacesAndPonctuation(s1));
            s2 = deAccent (removeSpacesAndPonctuation(s2));
            char[] str1 = s1.toCharArray();
            java.util.Arrays.sort(str1);
            s1 = new String(str1);
            char[] str2 = s2.toCharArray();
            java.util.Arrays.sort(str2);
            s2 = new String(str2);
            return s1.equals(s2);
     }
 
     public static boolean isAnagram(String a, String b) {
            int[] first = new int[26]; 
            int[] second = new int [26];
            int c = 0;
 
            // first[0] will contain the number of 'a's of a
            // first[1] will contain the number of 'b's of a
            // first[26] will contain the number of 'z's of a
            for ( c = 0; c < a.length(); ++c ) {
                int i = Character.toLowerCase(a.charAt(c))-'a';
                if ( i > 0 && i < 26 )
                     first[i]++;
            }
 
            for ( c = 0; c < b.length(); ++c ) {
                int i = Character.toLowerCase(b.charAt(c))-'a';
                if ( i > 0 && i < 26 )
                     second[i]++;
            } 
 
            for (c = 0; c < 26; c++) {
                if (first[c] != second[c])
                    return false;
            }
            return true;
     }
 
        public static boolean areMutualPalindromes (String s1, String s2) {
                s1 = new StringBuffer(s1).reverse().toString();
                return s1.equals(s2);
        }
 
     public static boolean isPhrasePalindrome (String s) {
            String s2 = deAccent (removeSpacesAndPonctuation(s));
            return palindromes.reverse(s2).equals(s2);
     }
 
     public static void printPalindromeNumbers (int start, int amount) {
            for ( int i = start, cnt = 0; cnt < amount; ++i )
                  // check whether the string representing i is a palindrome
                  if (isPalindrome (baseConverter.itoa(i,10))) {   
                      System.out.print ( String.format ("%d = %d\n", cnt+1, i) );
                      ++cnt;
                  }
     }
 
     public static void main(String[] args) {            // args is an array of Strings
            palindromes p = new palindromes();           // never forget to instanciate an object of your new class
            if (args.length == 1) {                      // only one argument
                 boolean p1 = p.isPalindrome (args[0]);
                 boolean p2 = p.isPhrasePalindrome (args[0]);
                 System.out.println ( "\"" + args[0] + "\"" + String.format(" is%s a palindrome", p1?"":" not") );
                 System.out.println ( "\"" + args[0] + "\"" + String.format(" is%s a palindrome phrase\n", p2?"":" not") );
                 System.out.println ( p.reverse (args[0]) );
                 System.out.println ( p.revString (args[0]) );
                 System.out.println ( p.reverseWords (args[0]) );
                 System.out.println ( p.deAccent (args[0]) );
            } else if (args.length > 1) {                // two or more arguments
                 boolean a = p.areAnagrams (args[0], args[1]);
                 boolean c = p.isAnagram (args[0], args[1]);
                 boolean b = p.areMutualPalindromes (args[0], args[1]);
                 System.out.println ( "\"" + args[0] + "\"" + " and " + "\"" + args[1] + "\"" + String.format(" are%s anagrams", a?"":" not") );
                 System.out.println ( "\"" + args[0] + "\"" + " and " + "\"" + args[1] + "\"" + String.format(" are%s anagrams", c?"":" not") );
                 System.out.println ( "\"" + args[0] + "\"" + " and " + "\"" + args[1] + "\"" + String.format(" are%s mutual palindromes", b?"":" not") );
            } else p.printPalindromeNumbers (10000,20);  // no arguments
     }
}