GridBagLayout is one of the most flexible — and complex — layout managers the Java platform provides. A GridBagLayout places components in a grid of rows. Following is the declaration for gLayout class − public class GridBagLayout extends Object implements LayoutManager2, Serializable. Component; import ner; import gConstraints; import gLayout; import ; import JButton.
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Here are a couple of warnings:. I also recommend setting it too although you aren’t using the method. If no component managed by the GridBagLayout had weightx set, then when the components’ container was made wider, the components would stay clumped together in the center of the container, like this:.
You customize a GridBagConstraints object by setting one or more of its instance variables: How components change is dictated by how the baseline of the prevailing row changes.
How to Use GridBagLayout
The following figure shows the grid for the preceding applet. Larger numbers indicate that the component’s row or column should get more space. Another way to control the behavior of a component in a grid bag layout is to girdbaglayout padding and insets. The orientation of a container is determined by its ComponentOrientation property. Point getLayoutOrigin Determines the origin of the layout area, in the graphics coordinate space of the target container.
GridBagLayout (Java Platform SE 7 )
The way the program specifies the size and position characteristics of its components is by specifying constraints for each component, To specify constraints, you set instance variables in a GridBagConstraints object and tell the GridBagLayout with the setConstraints method to associate the constraints with the component.
By doing so, we tell each button to occupy all the space available and give them all equal weighting. A real figure will go here. With Safari, you learn the way you learn best. Imagine your frame to be something like Excelthe gridx works as the Row variable, and gridy works as the Column variable.
We recommend specifying the gridx and gridy values for each component; this tends to result in more predictable layouts. Rather than specifying the constraints with the add method, our examples used to invoke the setConstraints method on the GridBagLayout object. Here is a picture of how these values are interpreted in a container that has the default, left-to-right component orientation.
Alternatively, to compile and run the example yourself, consult the example index. Returns the alignment along the y axis. This question appears to be off-topic.
Controls the position of the component if there is extra room within the allotted space. Take note of how they’re organized. String toString Returns a string representation of this grid bag layout’s values. Run the program using the jaga command.
Learning Java, 4th Edition by Daniel Leuck, Patrick Niemeyer
Each cell is identified by its column index ranging from 0 to the number of columns minus 1 and its row index ranging from 0 to the number of rows minus 1. Specifying Constraints The following code is typical of what goes in a container that uses a GridBagLayout.
The grid size is determined implicitly by the constraints of all the objects; the layout manager picks dimensions large enough so that everything fits. ContainerEventDemo How to Write a Container Listener Positions five components within a container, using weights, fill, and relative positioning. Components with a weight of 0 receive no extra space. The row index is returned as zero if y lies above the layout, and as the number of rows if y lies below the layout.
BOTH is one of the constants of the GridBagConstraints class; it tells the component to gribdaglayout the available space in both directions. Retrieves the constraints gridbaglqyout the specified component. The button in the second row spans all the columns; the button in the third row spans the two right columns.
The next section discusses constraints in depth, in the context of explaining how the example program works. The componentAdded method is very simple.
There’s a jqva for anchors, here’s all of them: Figures out the minimum size of the master based on the information from getLayoutInfo. Essentially, GridBagLayout places components in rectangles cells in a grid, and then uses the components’ preferred sizes to determine how big the cells should be.
In short, GridBagLayout is complex and has some quirks. It is also simply a bit ugly both in model and implementation. Instead of invoking methods on a GridBagConstraints object, you manipulate its instance variables, as described in Specifying Constraints.