Scrollable Panel

When using a JScrollPane the general rule is that the scrollbars will appear when the “preferred size” of the component added to the JViewport of the scroll pane is greater than the “size” of the viewport. There may be times when you wish to prevent a scrollbar from appearing even though the preferred size is greater than the size.

Text Prompt

Generally text fields are paired with a label when added to a GUI. The label describes the contents of the text field. In some applications you may have noticed that a text prompt appears inside an empty text field. This might be done when space is at a premium or you need to provide addition formatting information for the text.

ToolTips and ScrollPanes

Tooltips are generated by mouse movement over different Swing components. In a complex component, like a JTable, the tooltip is continually updated as the mouse moves from cell to cell. But what happens when the table is in a scrollpane and the viewport is moved? In this case the mouse may now be hovering over a different cell, but the tooltip is not updated. This may, or may not, be a problem depending on your requirements.

Text Field Auto Tab

Anybody who has ever written a DocumentFilter has probably seen the DocumentSizeFilter example from the Swing tutorial on “Implementing a DocumentFilter”. It is simple, straight forward and works well. However, wouldn’t it be nice to have some additional functionality, namely the ability for auto tabbing when the Document is full?

Chaining Document Filters

A previous entry on Text Validation briefly mentions why you should consider using DocumentFilters. A limitation of a DocumentFilter is that you can only add a single filter to the Document. There may be times when you need to filter on multiple conditions. Of course you can always create a new filter and combine the code for multiple filter conditions. However, an easier approach would be to reuse existing filters. That is, it would be nice to be able to chain multiple filters together to act as a single filter.

Component Border

There are many times when you want a JTextField and a JButton to work together. That is you provide the user with a text field for entering data and you provide a button to display a popup component to make it easier to enter the data. An example might be a date field. Some users might choose to type the date directly into the text field, while others might choose the point and click approach. There are a couple of common appoaches for achieving this and one not so common approach that I will suggest.

Resizing Components

A recent entry on Moving Windows discussed how you might add functionality to move a component or a non decorated window. Today we will look at adding resizing functionality to these same components.

Global Event Dispatching

As a user interacts with a GUI, by using the mouse or keyboard, Swing handles the interaction by dispatching events to the appropriate component for processing. In turn the component will notify any listeners that the event has been received and processed. There may be times when you want to intercept or alter the event before it is dispatched to the component. Swing provides a few different approaches that will allow you to control the dispatching of events.

Global Event Listeners

Listeners are used to listen for specific events on a given component. This makes it easy to listen for a MouseEvent on a text component for example. With this approach you need to add a separate listener to the component for every event you want to listen for. However there may be times when you want to listen for events at a more global level. That is, you may want to listen for events:

• of multiple types on a specific component – in this case you would need to create multiple listeners to add to the component.
• of a single type on all components – in this case you would need to create a single listener and then recursively add it to all components.

Wouldn’t it be nice if the above requirements could be handled by a single listener?

Disabled Panel

A previous entry discussed a DisabledGlassPane which allows you to disable key and mouse events for an entire frame. There may be times when you need to disable key and mouse events for a given Container only. Unfortunately you can’t just invoke setEnabled(false) on the container to disable the contained components. So we need another approach.