Palindromes

This Java program allows users to input a sentence and determines if it is a palindrom. All non-alphabetic characters including blanks, tabs, and punctuations are stripped from the sentence and the remaining characters are converted to Upper-Case for comparison of characters.

Implementation details:

• String functions are used throughout.
• Extraction of alphabetic characters are done by character code comparison (between 65 and 90, inclusively).
• The "enter" key signifies the end of the sentence.

// Palindrome P.C. 2004-11-07
//
//
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class test extends JFrame implements ActionListener{
   private JTextArea notes;
   private JTextField inField;
   private JTextArea outArea;
   private String out="";

   public test(){
      super("Palindrome");

      // GUI stuff
      notes=new JTextArea(5,20);
      notes.setFont(new Font("Courier",Font.BOLD,11));
      notes.append("Palindromes are words or sentences that\n");
      notes.append("read forwards and backwards\n");
      notes.append("For example: Ah, Satan sees Natasha\n");
      notes.append("A Toyota! Race fast, safe car. A Toyota.\n");
      notes.append("visit:http://www.palindromelist.com/ for more\n");
      inField=new JTextField("Borrow or rob?",20);
      inField.addActionListener(this);
      outArea=new JTextArea(20,35);
      outArea.setFont(new Font("Courier",Font.BOLD,11));
      JScrollPane scr=new JScrollPane(outArea);

      Container c=getContentPane();
      c.setLayout(new FlowLayout());
      c.add(notes);
      c.add(inField);
      c.add(scr);

      this.setLocation(200,200);
      setSize(350,500);
      setVisible(true);

   } // end constructor test

   private boolean isPalindromeWord(String s){
      // Check if given word s is a palindrom
      int L=s.length();
      for(int i=0;i<(int)(L/2);i++){
         if(s.charAt(i)!=s.charAt(L-1-i))return false;
      }
      return true;
   }



   private boolean isPalindrome(String s){
      // first strip s of all non-alphabetic characters
      int ns=s.length();
      char c[]=new char[ns]; int nc=0;
      s=s.toUpperCase();
      for(int i=0;i64 && c1<=90){c[nc]=c1; nc++;}
      }
      String s1=new String(c,0,nc); // s1 is now an upper-case alphabetic word
      outArea.append(s1+"\n");
      if(isPalindromeWord(s1))return true; else return false;
   }

   public void actionPerformed(ActionEvent event){
      String txt=inField.getText();
      String msg;
      msg=(isPalindrome(txt))?"is a palindrom\n":"is NOT a palindrom\n";
      outArea.append(msg);
   }

} // end class test


public class Palindrome {
  public static void main(String[] args){
      test s=new test();
  }
}