How do I make my code check that the user has input a alphabetical character? [Java]
<p><strong>Update</strong>: the code works now. Thanks for help guys.</p>

<hr>

<p>This is part of the code I'm having trouble with </p>

<pre><code>if ((amount &lt; 0) || (Character.isLetter(amount)))
</code></pre>

<p>Anyone know what I'm doing wrong? Here's a piece of my code:</p>

<pre><code>try
      {
       if ( theStock.exists( pn ) )        // Button CHECK
       {
           thePicture.clear();                       
           if ( actionIs.equals( Name.ADD ) ) {
               try 
               {
                   amount = Integer.parseInt(theInputPQ.getText());      // Checks that
                   if ((amount &lt; 0) || (Character.isLetter(amount))) {   // number has been
                       theOutput.setText("Please enter sufficient No."); // input
                    }
                    else {
                        theStock.addStock(pn, amount);
                        Product pr = theStock.getDetails( pn ); // Add to
                        theAction.setText(                      // stock of
                        pr.getDescription() + " : " +           // item
                        theMoney.format(pr.getPrice()) + 
                        " (" + pr.getQuantity() + ")" );
                    }                       
                }

                catch (NumberFormatException e) {
                    theOutput.setText("Please enter sufficient No.");

                    Product pr = theStock.getDetails( pn );              
                    theAction.setText(                    
                    pr.getDescription() + " : " +       
                    theMoney.format(pr.getPrice()) +    
                    " (" + pr.getQuantity() + ")" );

                    if ( actionIs.equals( Name.ADD ) ) {
                    } 
                }
            } else {                                   // F
                theAction.setText(                    //  Inform Unknown
                "Unknown product number " + pn );    //  product number
            }
        }
</code></pre>
