Monday, February 13, 2006

A Visual Guide to Layout Managers

Several AWT and Swing classes provide layout managers for general use:

This section shows example GUIs that use these layout managers, and tells you where to find the how-to page for each layout manager. You can find links for running the examples in the how-to pages and the example index.

BorderLayout

A picture of a GUI that uses BorderLayout
Every content pane is initialized to use a BorderLayout. (As Using Top-Level Containers (in the Creating a GUI with JFC/Swing trail) explains, the content pane is the main container in all frames, applets, and dialogs.) A BorderLayout places components in up to five areas: top, bottom, left, right, and center. All extra space is placed in the center area. For further details, see How to Use BorderLayout.

BoxLayout

A picture of a GUI that uses BoxLayout
The BoxLayout class puts components in a single row or column. It respects the components' requested maximum sizes and also lets you align components. For further details, see How to Use BoxLayout.

CardLayout

A picture of a GUI that uses CardLayout Another picture of the same layout

The CardLayout class lets you implement an area that contains different components at different times. A CardLayout is often controlled by a combo box, with the state of the combo box determining which panel (group of components) the CardLayout displays. An alternative to using CardLayout is using a tabbed pane (in the Creating a GUI with JFC/Swing trail), which provides similar functionality but with a pre-defined GUI. For further details, see How to Use CardLayout.

FlowLayout

A picture of a GUI that uses FlowLayout
FlowLayout is the default layout manager for every JPanel. It simply lays out components in a single row, starting a new row if its container isn't sufficiently wide. Both panels in CardLayoutDemo, shown previously, use FlowLayout. For further details, see How to Use FlowLayout.

GridBagLayout

A picture of a GUI that uses GridBagLayout
GridBagLayout is a sophisticated, flexible layout manager. It aligns components by placing them within a grid of cells, allowing some components to span more than one cell. The rows in the grid can have different heights, and grid columns can have different widths. For further details, see How to Use GridBagLayout.

GridLayout

A picture of a GUI that uses GridLayout
GridLayout simply makes a bunch of components equal in size and displays them in the requested number of rows and columns. For further details, see How to Use GridLayout.

SpringLayout

A picture of a GUI that uses SpringLayout
Another GUI that uses SpringLayout
SpringLayout is a flexible layout manager designed for use by GUI builders. It lets you specify precise relationships between the edges of components under its control. For example, you might define that the left edge of one component is a certain distance (which can be dynamically calculated) from the right edge of a second component. For further details, see How to Use SpringLayout.

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