public void actionPerformed(ActionEvent e) {
	        String cmd = e.getActionCommand();
	        String input= userNameField.getText();
	        
	       if (OK.equals(cmd) && !input.trim().equals("")) {
	    	   if (checkAccount(input)==true) {	//if account exists
	    		   controllingFrame.setVisible(false);
	    		   globalAccount=input.toUpperCase(); 
	                MyLibraryManager_User user= new MyLibraryManager_User();	//initiates the main user database interface
	                resetFocus();
	                JOptionPane.showMessageDialog(controllingFrame,	//output welcome message 
	                "Welcome back, "+input.toUpperCase()+"!");
	            }
	    	   
	    	   	else if (checkAccount(input)==false && input.equalsIgnoreCase("Admin")) {	//if logged in as admin
	    	   		controllingFrame.setVisible(false);
	    	   		globalAccount=input.toUpperCase();
	    	   		MyLibraryManager_Administrator admin=new MyLibraryManager_Administrator();	//initiates the main admin database interface
	    	   		JOptionPane.showMessageDialog(controllingFrame,	//output welcome message 
	    	                "Welcome back, Administrator!");    	   		
	    	   	}
	    	   
	    	   	else if (checkAccount(input)==false) {	//output message if the user account does not exist 
	                JOptionPane.showMessageDialog(controllingFrame,
	                    "The user name entered does not exist. Please try again.",
	                    "Error Message",
	                    JOptionPane.ERROR_MESSAGE);
	                userNameField.setText("");
	            }
	       }
	      
	       	else if (CREATEACCOUNT.equals(cmd)) { //if user clicks Create Account
	       		MyLibraryManager_CreateAccount.createAndShowGUI();	   //show GUI for create account window     		
	       	}
	       	else {
	    		JOptionPane.showMessageDialog(controllingFrame,	//output message if the text field is blank.
	                    "The user name field is blank. Please try again.",
	                    "Error Message",
	                    JOptionPane.ERROR_MESSAGE);
	    				userNameField.setText("");
	    	}
	    }