public void actionPerformed(ActionEvent e) {
	        String cmd = e.getActionCommand();
	        String input= userNameField.getText();
	        
	       if (OK.equals(cmd) && !input.trim().equals("")) { 
	    	   	if (checkAccount(input)==false && input.equalsIgnoreCase("Admin") || input.equalsIgnoreCase("Administrator")) {
	    	   		JOptionPane.showMessageDialog(controllingFrame,	//the account name cannot be admin or administrator 
	    		            "You may not use that as your user name. Please try another one.",
	    		            "Error Message",
	    		            JOptionPane.ERROR_MESSAGE);
	    		            userNameField.setText("");
	    	   	}
	    	   	else if (checkAccount(input)==false) {	//if the account does nto exist, log into database interface
	    		   controllingFrame.setVisible(false);
	    		   MyLibraryManager_LogIn.controllingFrame.setVisible(false);
	                JOptionPane.showMessageDialog(controllingFrame,	//output welcome message 
	                "Hello, "+input+"! Welcome to MyLibraryManager.");
	                globalAccount=input; 
	                saveAccountName(input);
	                createBookList(input);
	                MyLibraryManager_User user= new MyLibraryManager_User();	//initiate database interface 
	                resetFocus();
	    	    }
	            else if (checkAccount(input)==true){	//output error message if the acocunt name already exists 
		            JOptionPane.showMessageDialog(controllingFrame,
		            "The user name entered already exists. Please try another name.",
		            "Error Message",
		            JOptionPane.ERROR_MESSAGE);
		            userNameField.setText("");
		        }     
	        }

	    	else if (CANCEL.equals(cmd)) { //close the window 
	            controllingFrame.setVisible(false);
	            
	    	}
	    	else {
	    		JOptionPane.showMessageDialog(controllingFrame,	//output error message if the text field is blank 
	                    "The entry field is blank. Please try again.",
	                    "Error Message",
	                    JOptionPane.ERROR_MESSAGE);
	    		userNameField.setText("");
	    	}
		}