Program Help, working with spaces and only letters

Question

I'm writing a program that takes an input string and gets the length and/or gets the number of vowels and consonants in the string. I've gotten it working except for consideration of spaces (which are allowed) and error checking for input other than letters. Here is what I've got so far. ANY suggestions would be greatly appreciated. Thank You
import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class LetterStringManip extends JFrame
{//declaring variables
     private JLabel stringOfLettersL, lengthL, lengthRL, vowelsL, vowelsRL, consonantsL, consonantsRL;
       private JTextField stringOfLettersTF;
       private JButton lengthB,vowelB, quitB;
       private LengthButtonHandler lbHandler;
       private VowelButtonHandler vbHandler;
       private QuitButtonHandler qbHandler;
       private static final int WIDTH = 750;
       private static final int HEIGHT = 150;
       public LetterStringManip()
       {// setting up GUI window with buttons
           stringOfLettersL = new JLabel("Enter a String of Letters", SwingConstants.CENTER);
               lengthL = new JLabel("Length of String: ", SwingConstants.CENTER);
               lengthRL = new JLabel("", SwingConstants.LEFT);
               vowelsL = new JLabel("Number of Vowels: ", SwingConstants.CENTER);
               vowelsRL = new JLabel("", SwingConstants.LEFT);
               consonantsL = new JLabel("Number of Consonats: ", SwingConstants.CENTER);
               consonantsRL = new JLabel("", SwingConstants.LEFT);
               stringOfLettersTF = new JTextField(15);
               lengthB = new JButton("Length");
               lbHandler = new LengthButtonHandler();
               lengthB.addActionListener(lbHandler);
               vowelB = new JButton("Vowels");
               vbHandler = new VowelButtonHandler();
               vowelB.addActionListener(vbHandler);
               quitB = new JButton("Quit");
               qbHandler = new QuitButtonHandler();
               quitB.addActionListener(qbHandler);
               setTitle("String Of Letters");//Window title
               Container pane = getContentPane();
               pane.setLayout(new GridLayout(3,4)); //Window layout
               pane.add(stringOfLettersL);
               pane.add(stringOfLettersTF);
               pane.add(lengthL);
               pane.add(lengthRL);
               pane.add(vowelsL);
               pane.add(vowelsRL);
               pane.add(consonantsL);
               pane.add(consonantsRL);
               pane.add(lengthB);
               pane.add(vowelB);
               pane.add(quitB);
               setSize(WIDTH, HEIGHT);
               setVisible(true);
               setDefaultCloseOperation(EXIT_ON_CLOSE);
       }//closes public LetterStringManip()
       private class LengthButtonHandler implements ActionListener
           public void actionPerformed(ActionEvent e)//Length Button is clicked, getLength() method is performed
                  getLength();
               }//closes public void actionPerformed(ActionEvent e)
       }//closes private class LengthButtonHandler implements ActionListener
       private class VowelButtonHandler implements ActionListener
           public void actionPerformed(ActionEvent e)//Vowels Button is clicked, getVowels() method is performed
                  getVowels();
               }//closes public void actionPerformed(ActionEvent e)
       }//closes private class VowelButtonHandler implements ActionListener
       private class QuitButtonHandler implements ActionListener//Quit Buttton is pressed
           public void actionPerformed(ActionEvent e)
                   System.exit(0);
               }//closes public void actionPerformed(ActionEvent e)
       }//closes private class QuitButtonHandler implements ActionListener
                 public void getLength()//gets the length of the string
                   String letString = (stringOfLettersTF.getText());
                   String lengthString;
             int length;
                     length = letString.length();
                     lengthString = Integer.toString(length);
                     lengthRL.setText(lengthString);
                }//closes public void getLength()
                 public void getVowels()//gets the number of vowels in the string
             String letString = (stringOfLettersTF.getText());
                   String vowString;
                     String conString;
             int countVow = 0;
                     int countCon = 0;
                     int i;
                     int length = letString.length();
                     char[] letter = new char[length];
             for (i = 0; i < letString.length(); i++)
                 letter[i] = letString.charAt(i);
                 if (letter=='a' || letter[i]=='e' || letter[i]=='i' || letter[i]=='o' || letter[i]=='u')
countVow++;
                    }//closes for
                    countCon = letString.length() - countVow;
vowString = Integer.toString(countVow);
                    conString = Integer.toString(countCon);
                    vowelsRL.setText(vowString);
                    consonantsRL.setText(conString);
               }//closes public void getVowels()
     public static void main(String[] args)
     LetterStringManip stringObject = new LetterStringManip();
     }// closes public static void main(String[] args)
}//closes public class LetterStringManip extends JFrame

Answer 1

OK, per the instructions above: I will re-post my code that I have now. I have dealt with the space not being counted now, I only need to figure out how to validate my input so that only letters are allowed. If anyone has any suggestions, or can help me out in any way, it'd be great. The suggestions with creating word and sentence objects is still a little beyond what we have gone over thus far in my Java course, I feel like I can almost grasp it to code it, but end up getting really confused. anyways, hear is my 'crude' code so far:
                 public void getLength()
                   String letString = (stringOfLettersTF.getText());
                   String lengthString;
                      int finalLength;
                      int countSpace = 0;
                            int length = letString.length();
                   char[] letter = new char[length];
                    int i;
                             for (i = 0; i < letString.length(); i++)
                                letter[i] = letString.charAt(i);
                                if (letter==' ')
countSpace++;
          finalLength = length - countSpace;
               lengthString = Integer.toString(finalLength);
               lengthRL.setText(lengthString);
               public void getVowels()
String letString = (stringOfLettersTF.getText());
               String vowString;
               String conString;
int countVow = 0;
               int countCon = 0;
               int countSpace = 0;
               int i;
               int length = letString.length();
               char[] letter = new char[length];
for (i = 0; i < letString.length(); i++)
letter[i] = letString.charAt(i);
if (letter[i]=='a' || letter[i]=='e' || letter[i]=='i' || letter[i]=='o' || letter[i]=='u')
countVow++;
               if (letter[i]==' ')
countSpace++;
               countCon = (letString.length() - countVow) - countSpace;
vowString = Integer.toString(countVow);
               conString = Integer.toString(countCon);
               vowelsRL.setText(vowString);
               consonantsRL.setText(conString);