Help With Grid Width in Java

Java's Gridbag layout manager is based on placing components within a grid.

Designing a graphical user interface for a program can be one of the most tedious tasks a programmer faces. While Java makes this process easier by including a standard library for creating GUIs, you must still make everything just right. Programmers using Swing's Gridbag layout manager have a lot of control in specifying the details of their interface, including the width of the grids that size individual interface components.

Swing Layout Managers

Swing comes with a number of layout managers: methods for specifying how the program's different components will be laid in the interface. Many of these managers, such as the Border layout manager or the Flow layout manager, restrict the level of detail with which the programmer can control the final layout. The Gridbag layout manager differs from the other managers in the level of control it gives the programmer. This control also means that the programmer has to spend more time setting configuration values.

The Gridbag Manager

The Gridbag manager's placement of individual components is controlled by a "GridBagConstraints" object. This object contains variables for every aspect of a component's placement and sizing, which the programmer must set individually. Once the values are set, the programmer adds the component to the intended frame or pane with the GridBagConstraints object. Programmers can use the same object to place many different components, only modifying the fields that need to change before adding each component.

Sizing

The Gridbag layout considers the space on the screen to be one grid between the X (horizontal) and Y (vertical) axis. By default, every component is one grid by one grid. The exact size of a grid depends on the size of the screen and the number of components the programmer adds. The larger the screen, the larger Java will make each grid. Alternatively, if the programmer adds several components, Java will reduce the size of each grid so that everything will fit. The programmer can fix a grid size by making his program's screen a set size that the user can't change.

Automatic Placement

While Java automatically sizes grid width depending on screen size and component density, the programmer can use the "ipady" variable of GridBagConstraints to inflate the grid width for an individual component, leaving the grid size for the other components intact. By default, this variable is set to zero, but the programmer can increase a component's grid width by setting this to a higher number. The higher the number, the larger the grid width for that component will be.

References

• "Core Java Volume I: Fundamentals": Cay S. Horstmann, Gary Cornel
• The Java Tutorials: How to Use GridBagLayout