Cipher help | It keeps throwing errors

Question

As soon as you try to input a key it throws an error.
import javax.swing.*;
public class Animal
    private String inputString;
    private int intOffset;
    public Animal()
        inputString = null;
        intOffset = 0;
    public static void main(String [] args)
        Animal c2 = new Animal();
        int choose = JOptionPane.showConfirmDialog(null,"If you want to Encrypet Text Click (Yes) ,or Decrypt Click (No) or Cancel to exit :");
        if (choose == JOptionPane.YES_OPTION)
            String plainText = c2.encrypt();
            JOptionPane.showMessageDialog(null,plainText);
        else if(choose == JOptionPane.NO_OPTION)
            String cipherText = c2.decrypt();
            JOptionPane.showMessageDialog(null,cipherText);
        else
            System.exit(0);
    public String encrypt()
        inputString = ((String)JOptionPane.showInputDialog("Enter PlainText") ).toLowerCase().trim();
        intOffset = Integer.parseInt(JOptionPane.showInputDialog("Enter Key") );
        String letters = "abcdefghijklmnopqrstuvwxyz";
        StringBuffer sb = new StringBuffer();
        int holder = inputString.length();
        for(int i = 0; i < holder; i++)
                String tmp = ""+inputString.charAt(i);
                int offset = letters.indexOf(tmp);
                offset += intOffset;
                if( offset > 25 ){
                    int newOffset = 0;
                    newOffset = offset % 26;
                    sb.append( letters.charAt(newOffset) );
                else
                        sb.append( letters.charAt(offset) );
            }//forloop
            return sb.toString();
    public String decrypt()
        inputString = ((String)JOptionPane.showInputDialog("Enter CipherText") ).toLowerCase().trim();
        intOffset = Integer.parseInt(JOptionPane.showInputDialog("Enter Key") );
        String letters = "abcdefghijklmnopqrstuvwxyz";
        StringBuffer sb = new StringBuffer();
        int holder = inputString.length();
        for(int i = 0; i < holder; i++)
                String tmp = ""+inputString.charAt(i);
                int offset = letters.indexOf(tmp);
                offset -= intOffset;
offset %= 26;
sb.append( letters.charAt(offset) );
        return sb.toString();
}

Answer 1

As soon as you try to input a key it throws an error.If you expect to get help on forums, you should consider being specific.
What error does it throw, where in the code is the error thrown...what have you tried to do to fix it...etc...