Help on Java modifications

[Troy Johnson]

Hello. I am working on the following Java problem. I am making two modifications to the program. The first is to Ignore cases, which I have completed. The second is to Use a command-line argument. Could anyone offer any suggestions on using a command-line argument with this program. Thanks.

import javax.swing.JOptionPane;
public class Palindrome {
  public static void main(String[] args) {
    // Prompt the user to enter a string
    String s = JOptionPane.showInputDialog(
      null, "Enter a string:",
      " Input", JOptionPane.QUESTION_MESSAGE);

    if (isPalindrome(s)) {
      System.out.println(s + " is a palindrome");
    }
    else {
      System.out.println(s + " is not a palindrome");
    }
  }
  /** Check if a string is a palindrome */
  public static boolean isPalindrome(String s) {
    // The index of the first character in the string
    int low = 0;
    // The index of the last character in the string
    int high = s.length() - 1;
    while (low < high) {
      if (!equals(s.charAt(low), s.charAt(high)))
        return false; // Not a palindrome
      low++;
      high--;
    }
    return true; // The string is a palindrome
  }
  /** Return true if two letters are the same regardless case */
  public static boolean equals(char c1, char c2) {
    return lowercase(c1) == lowercase(c2);
  }
  public static char lowercase(char c) {
    if (c >= 'A' && c <= 'Z') {
      int offset = (int)'a' - (int)'A';
      char lowercase = (char)((int)c + offset);
      return lowercase;
    }
    else
      return c;
  }
}

[ October 11, 2003: Message edited by: Troy Johnson ]
[ October 11, 2003: Message edited by: Troy Johnson ]

[Joel McNary]

Command-Line arguments are easy to use. Take a look at the signature for the main method:

public static void main (String argv[])

That String array is where you receive your parameters.
(As I learned in C, I call it argv[], instead of args...)
So, the length of this array will tell you how many parameters there are, and each parameter receives its own spot in the array.
Note that, unlike in C, the program name is not passed in here. The first parameter really is the first parameter.

[Michael Dunn]

Try this

class Palindrome
{
  public Palindrome(String word)
  {
    System.out.println(word + " = "+ isPalindrome(word)+", as a palindrome");
  }
  private boolean isPalindrome(String s)
  {
    s = s.toLowerCase();
    for(int i = 0; i < s.length()/2; i++)
    {
      if(s.charAt(i) != s.charAt(s.length()-1-i)) return false;
    }
    return true;
  }
  public static void main(String[] args)
  {
    new Palindrome(args[0]);
  }
}