Caesar Cipher - Java Code Bank

                /**
 * @author Greg_G
 *
 */

	import javax.swing.*;

	
	
	public class Ceasar1 {

	
		private String plaintext;

		private static int keyOffset;



	public Ceasar1()

	{

		plaintext = null;

		keyOffset = 0;

	}



	public static void main(String [] args)

	{

		Ceasar1 cipherArray = new Ceasar1();

		String tmp = cipherArray.encrypt();

		System.out.println("This is after encryption:" + tmp );
	
		System.out.println(decrypt("This is decrypted back to its original form" + tmp ) );

		System.exit(0);

	}



	public String encrypt()

	{

		plaintext = ((String)JOptionPane.showInputDialog("enter string to encrypt:") ).toLowerCase().trim();

		keyOffset = Integer.parseInt(JOptionPane.showInputDialog("enter offset to shift the letters by:") );



		String alphabet = "abcdefghijklmnopqrstuvwxyz";



		StringBuffer sbuff = new StringBuffer();

		int holder = plaintext.length();



		for(int i = 0; i < holder; i++)

	{

			String tmp = ""+plaintext.charAt(i);


			int offset = alphabet.indexOf(tmp);
			

			offset += keyOffset;



			if( offset > 25 )

	{

				int newOffset = 0;

				newOffset = offset % 25;

				sbuff.append(alphabet.charAt(newOffset) );

	}



			else

	{

				sbuff.append(alphabet.charAt(offset));

	}


	}

		return sbuff.toString();

	

	}
	
	public static String decrypt(String tmp) {
		
		String alphabetdec = "abcdefghijklmnopqrstuvwxyz";


		StringBuffer sbuff = new StringBuffer();

	
		int holder = tmp.length();


		for(int i = 0; i < holder; i++)

		{
			
			String tmp1 = ""+tmp.charAt(i);	

			int offset = alphabetdec.indexOf(tmp1);



			offset -= keyOffset;
	
			if( offset < 0 )

		{

				int newOffset = 0;

				newOffset = offset + 25;

				sbuff.append( alphabetdec.charAt(newOffset) );

		}


			else

		{

				sbuff.append( alphabetdec.charAt(offset) );

		}


		}
		
		
		return sbuff.toString();


	}

	
}