GRIDBAGLAYOUT JAVA PDF
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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These coordinates become the gridx and gridy values for the constraints. Similarly, the height of the component will be at least the minimum height plus ipady pixels.
Before calling addGB gridbahlayout, we set any fields of gbc for which the defaults are inappropriate. Previously, this was the maximum number of grid positions both horizontal and vertical that could be laid out by the grid bag layout. It is also simply a bit ugly both in model and implementation.
GridBagLayout (Java Platform SE 7 )
The Tutorial’s examples used to specify the constraints object a different way, which you might see in other programs as well. Likewise, the vertical padding, ipadyis added on both the top and the bottom. This is true of layouts as well as life. One of the most important features of GridBaglayout is that it lets you create arrangements in which components span two or more rows or columns.
By doing so, we tell each button to occupy all the space available and give them all equal weighting. And before setting the constraints of the next component, the code resets the value of ipady to the default:.
Aligns two pairs of labels and text fields, plus adds a label across the full width of the container. Notice that the horizontal padding, ipadxis added on both the left and right sides of the button. Finally, there’s one other important function, fill. Point getLayoutOrigin Determines the origin of the layout area, in the graphics coordinate space of the target container.
All of this referring to Excel of course. This is distinct from the grid origin given by the cell coordinates 0,0. Retrieves the constraints for the specified component.
Figure out the dimensions of the layout grid. If you enlarge the window as shown in the following figure, you will notice that the bottom row, which contains Button 5, gets all the new gridbaglayoug space. This resizing behavior is based on weights the program assigns to individual components in the GridBagLayout.
Possible values are GridBagConstraints. Similarly, not all columns necessarily have the same width. Unless you specify at least one non-zero value for weightx or weightyall the components clump together in the center of their container. The method is like this:.
The information in this field is based on the most recent validation of the gridbag. As long as you keep things simple, the effect these variables have is fairly intuitive: You’ll see a more detailed example in the next section. It then adds the component to its container, specifying the GridBagConstraints object as the second argument to the add method.
GridBagLayout does not allow components to span multiple rows unless the component is in the leftmost column or you have specified positive gridx and gridy values for the component.
The actual value of these components’ weightx is unimportant. If this field is non- null the values are applied to the gridbag after all of the minimum columns widths have been calculated.
Learning Java, 4th Edition by Daniel Leuck, Patrick Niemeyer
As you can see, the grid has three rows and three columns. Combining layout managers is an extremely useful trick.
This example uses one GridBagConstraints instance for all the components the GridBagLayout manages, however in real-life situations it is recommended that you do not reuse GridBagConstraintsas this can very easily lead to you introducing subtle bugs if you forget to reset the fields for each new instance.
This behavior is also specified by the program. How to Use GridBagLayout? The following discussion assumes that the GridBagLayout controls a container that has a left-to-right component orientation. 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.
Components positioned using one of the baseline-relative values resize differently than when positioned using an absolute or orientation-relative value.
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded. The following rules dictate the resize behavior: For each column, the weight is related to the highest weightx specified for a component within that column, with each multicolumn component’s weight being split somehow between the columns the component is in.