Breaking up a String array

Question

Hi guys!
I have been working on this for a while! I have an assignment which requires:
-take input of a seven digit integer
- break this number apart and perform calculations in order to "encrypt" the number.
-etc..
I thought I should break the string up first, then convert each element to an int for calculations.
I am sure there is a better way to do this.
Could I use a String Tokenizer? How would I do that?
Thanks!!
Here's what I have so far:
import javax.swing.*;
public class Assignment3 {
  public static void main( String args[] ) {
    String choiceString = "",
    output = "",
    stringArray[] = new String[7];
    int intArray[] = new int[7],
    choiceInt;
    while ( choiceString != null ) {
      // prompt user to input a seven digit integer
      choiceString=JOptionPane.showInputDialog("Please     enter the number corresponding to your choice:\n1.Encryption\n2.Decryption\n3.Exit");
      choiceInt = Integer.parseInt( choiceString );
     if( choiceInt != 1 || choiceInt != 2 || choiceInt != 3)
        JOptionPane.showMessageDialog( null, "Invalid selection", "Error",
        JOptionPane.ERROR_MESSAGE );
      // 1=encrypt 2=decrypt 3=exit
      switch ( choiceInt ) {
        case 1:
         stringArray = JOptionPane.showInputDialog( "Please enter a seven digit number:" ) ;
          intArray = convert( stringArray );    // converts string to int
          digitSwap1( intArray );   
          nineModTen( intArray );
          digitSwap2( intArray );
          output += "Original: " + input + "\nOutput: " +  intArray;
          break;
        case 2:
          stringArray = JOptionPane.showInputDialog( "Please enter an encrypted number: " );
          intArray = convert( stringArray );
          digitSwap2( intArray );
          decrypt( intArray );
          digitSwap1( intArray );
          output += "Decrypted: " + input + "\nOutput: " + intArray;
          break;
        case 3:
          output += "Thank you, have a nice day";
          break;
        default:
          JOptionPane.showMessageDialog( null, "Please make a selection", "Error",
          JOptionPane.ERROR_MESSAGE );
          break;
      } // end switch
      JOptionPane.showMessageDialog( null, output, "Results",
      JOptionPane.INFORMATION_MESSAGE );
    } // end loop
    System.exit(0);
  } // end main
  public static void digitSwap1( int array[] )
    int digit1,digit2,digit3,digit4,digit5,digit6,digit7;
    digit1 = array[0];
    digit2 = array[1];
    digit4 = array[3];
    digit5 = array[4];
    digit6 = array[5];
    digit7 = array[6];
    array[0] = digit7;
    array[1] = digit6;
    array[2] = digit5;
    array[4] = digit3;
    array[5] = digit2;
    array[6] = digit1;
    } // end digitSwap1
  public static void nineModTen( int array[] )
    int x = 0;
    while ( x <= 6 ) {
      array[x] = ( array[x] + 9 ) % 10;
      x++;
    } // end loop
  }  // end nineModTen
  public static void digitSwap2( int array[] )
    int digit1,digit2,digit3,digit4,digit5,digit6,digit7;
    digit1 = array[0];
    digit2 = array[1];
    digit3 = array[2];
    digit4 = array[3];
    digit5 = array[4];
    digit6 = array[5];
    array[0] = digit2;
    array[1] = digit1;
    array[2] = digit4;
    array[3] = digit3;
    array[4] = digit6;
    array[5] = digit5;
  }  // end digitSwap2
  public static void decrypt( int array[] )
    int x = 0;
    while ( x <= 6 ) {
      if ( array[x] < 9 )
        array[x] += 1;
      else
        array[x] = 0;
      x++;
    }  // end loop
  } // end decrypt
  public static int[] convert( String array1[] )
    int array2[] = new int[7];   
    int count = 0;
    while ( count <= 6 ) {
      array2[count] = Integer.parseInt( array1[count] );
      count ++;
    } // end loop
    return( array2 );
    } // end convert
} // end class

Answer 1

I have solved my problem! The real problem was that I
was trying to output my resulting int array like this:
output = "result: " + intArraybut I discovered that when I concatenated each individual
element in the array, it worked fine:
output = "result: " + array[0] + array[1] ....Also, I found an easy way to break up the input. Rather
than use the charAt() method to extract each digit, and
then convert for calculation, I converted the String to int
and then, in a loop, extracted each digit from last to
first by: (array[count] = number% 10), then (number = number / 10).
Thanks everyone for your help! I hope this will help
someone else too. Below is the working code.
; > -HB
// this program takes a 7 digit input and "encrypts" it
// by 1st, swapping some of the digits, 2nd, add nine
// and mod ten to each digit, 3rd, swapping digits again.
import javax.swing.*;
public class Assignment3 {
  public static void main( String args[] ) {
    String choiceString = "",
    output = "",
    input;
    int number;
    int intArray[] = new int[7],
    choiceInt = 0;
    while ( choiceString != null ) {
      // prompt user to choose an option
      choiceString=JOptionPane.showInputDialog("Please enter the number corresponding to your choice:\n1.Encryption\n2.Decryption\n3.Exit");
      choiceInt = Integer.parseInt( choiceString );
      // 1=encrypt 2=decrypt 3=exit
      switch ( choiceInt ) {
          case 1:
          input = JOptionPane.showInputDialog( "Please enter a seven digit number:" );
          number = Integer.parseInt( input );
          intArray = convert( number );    // extract each digit
          intArray = digitSwap1( intArray );   
          nineModTen( intArray );
          intArray = digitSwap2( intArray );
          output = "Original: " + input + "\nOutput: " + intArray[0] +
                   intArray[1] + intArray[2] + intArray[3] +
                   intArray[4] + intArray[5] + intArray[6];
          JOptionPane.showMessageDialog( null, output, "Results",
          JOptionPane.INFORMATION_MESSAGE );
          break;
        case 2:
          input = JOptionPane.showInputDialog( "Please enter an encrypted number: " );
          number = Integer.parseInt( input );
          intArray = convert( number );
          intArray = digitSwap2( intArray );
          decrypt( intArray );
          intArray = digitSwap1( intArray );
          output = "Decrypted: " + input + "\nOutput: " + intArray[0] +
                   intArray[1] + intArray[2] + intArray[3] + intArray[4] +
                   intArray[5] + intArray[6];
          JOptionPane.showMessageDialog( null, output, "Results",
          JOptionPane.INFORMATION_MESSAGE );
          break;
        case 3:
          break;
        default:
          JOptionPane.showMessageDialog( null, "Please make a valid selection", "ERROR", JOptionPane.ERROR_MESSAGE);
          break;
      } // end switch
      if ( choiceInt == 3 )
        break;
      } // end loop
      JOptionPane.showMessageDialog( null, "Thank you, Have a nice day!", "EXIT",
      JOptionPane.PLAIN_MESSAGE );
    System.exit(0);
  } // end main
    public static int[] convert( int num )
      int array[] = new int[7];
      int count = 6;
      while ( count >= 0 ) {
        array[ count ] = num % 10;
        num = num / 10;
        count --;
      return array;
  } // end convert
  public static int[] digitSwap1( int array[] )
    int digit1,digit2,digit3,digit5,digit6,digit7;
    digit1 = array[0];
    digit2 = array[1];
    digit3 = array[2];
    digit5 = array[4];
    digit6 = array[5];
    digit7 = array[6];
    array[0] = digit7;
    array[1] = digit6;
    array[2] = digit5;
    array[4] = digit3;
    array[5] = digit2;
    array[6] = digit1;
    return array;   
  } // end digitSwap1
  public static void nineModTen( int array[] )
    int count = 0;
    while ( count < 7 ) {
      array[count] = ( array[count] + 9 ) % 10;
      count++;
    } // end loop
  }  // end nineModTen
  public static int[] digitSwap2( int array[] )
  int digit1,digit2,digit3,digit4,digit5,digit6;
    digit1 = array[0];
    digit2 = array[1];
    digit3 = array[2];
    digit4 = array[3];
    digit5 = array[4];
    digit6 = array[5];
    array[0] = digit2;
    array[1] = digit1;
    array[2] = digit4;
    array[3] = digit3;
    array[4] = digit6;
    array[5] = digit5;
    return array;
  }  // end digitSwap2
  public static void decrypt( int array[] )
    int count = 0;
    while ( count <= 6 ) {
      if ( array[count] < 9 )
        array[count] += 1;
      else
        array[count] = 0;
      count++;
    }  // end loop
   } // end decrypt
  } // end class