Java newbie, GUI question

[imzkris]

Hi there.

For a homework assignment I'm supposed to write an applet that tells whether or not a String input by the user is a palindrome. I think I have the logic worked out (and if I don't, I can fix that part myself), but this is my first GUI. The following compiles, but I keep getting an OutOfBounds exception (it says on line 38, which is where the variable indexTwo is defined) whenever the button is clicked. I'm not sure why; if it's just a little error or I need to approach it differently.

It's a little bit messy, I just want to make it work. Also, I originally had two classes and used a array, but the prof said the assignment should be one class per question and no arrays were needed (which I think is silly for a couple of the questions, but whatever).

// leading comments etc

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class PalindromeTest extends JApplet implements ActionListener {
	private JTextField inputString;
	private JButton theButton; //oh, and should I move this to the init() method?
	private JLabel truthLabel;
	
	public void init() {
		truthLabel = new JLabel("Input your text and click the button.");
		theButton = new JButton("Is it a palindrome?");
		inputString = new JTextField(20);
		theButton.addActionListener(this);
		Container contentPane = getContentPane();
		contentPane.setLayout(new FlowLayout());
		contentPane.add(inputString);
		contentPane.add(theButton);
		contentPane.add(truthLabel);
	}
	
	public void actionPerformed(ActionEvent e) {
	
		String strIn = inputString.getText();
		String str = strIn.toUpperCase();	//possibly redundant?
		boolean isPalindrome = true;
		int indexOne = 0;			//beginning of the string (index marker 1)
		int indexTwo = str.length();	//ending of the string (index marker 2)
		
		
		while (indexOne < indexTwo){	
			char charOne = str.charAt(indexOne);
			char charTwo = str.charAt(indexTwo);
			
			if (charOne != charTwo){	//exceptional case
				isPalindrome = false;
				break;
			}
			
			else {
				indexOne += 1; 	//move the first marker to the right
				indexTwo -= 1;	//move the second marker to the left
			}
			
		} //end of the while loop
		
		if (isPalindrome)
			truthLabel.setText("That is a palindrome.");
		else
			truthLabel.setText("That is not a palindrome.");
		
	}
}

[imaginationac]

You need exactly to add two more characters to your source to fix the problem.
HINT: Indexing in Java is 0 based. That is starts at 0.

There isn't much more I can say without giving it away.

[AmenKa]

I love silly mistakes!

I assume that you have already figured it out, but if you haven't then ill give another hint just because I had to do a palindrome checker... An array of size 5 has the values 0 through 4. If that didn't blatantly give it away then you don't belong in computer science.

Sorry if those of you out there don't like that I made it easy, but I doubt that it isn't just a stupid mistake that the poster already knows the answer to but didn't notice.