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java.lang.Object![]()
![]()
![]()
java.awt.GridBagLayout
, LayoutManager2
, Serializable

public class GridBagLayout

, Serializable

The GridBagLayout class is a flexible layout
manager that aligns components vertically and horizontally,
without requiring that the components be of the same size.
Each GridBagLayout object maintains a dynamic,
rectangular grid of cells, with each component occupying
one or more cells, called its display area.
Each component managed by a GridBagLayout is associated with
an instance of GridBagConstraints
. The constraints object
specifies where a component's display area should be located on the grid
and how the component should be positioned within its display area. In
addition to its constraints object, the GridBagLayout also
considers each component's minimum and preferred sizes in order to
determine a component's size.
The overall orientation of the grid depends on the container's
ComponentOrientation
property. For horizontal left-to-right
orientations, grid coordinate (0,0) is in the upper left corner of the
container with x increasing to the right and y increasing downward. For
horizontal right-to-left orientations, grid coordinate (0,0) is in the upper
right corner of the container with x increasing to the left and y
increasing downward.
To use a grid bag layout effectively, you must customize one or more
of the GridBagConstraints objects that are associated
with its components. You customize a GridBagConstraints
object by setting one or more of its instance variables:
GridBagConstraints.gridx
,
GridBagConstraints.gridy
gridx = 0,
gridy = 0. For horizontal left-to-right layout,
a component's leading corner is its upper left. For horizontal
right-to-left layout, a component's leading corner is its upper right.
Use GridBagConstraints.RELATIVE (the default value)
to specify that the component be placed immediately following
(along the x axis for gridx or the y axis for
gridy) the component that was added to the container
just before this component was added.
GridBagConstraints.gridwidth
,
GridBagConstraints.gridheight
gridwidth)
or column (for gridheight)
in the component's display area.
The default value is 1.
Use GridBagConstraints.REMAINDER to specify
that the component's display area will be from gridx
to the last cell in the row (for gridwidth)
or from gridy to the last cell in the column
(for gridheight).
Use GridBagConstraints.RELATIVE to specify
that the component's display area will be from gridx
to the next to the last cell in its row (for gridwidth
or from gridy to the next to the last cell in its
column (for gridheight).
GridBagConstraints.fill
GridBagConstraints.NONE (the default),
GridBagConstraints.HORIZONTAL
(make the component wide enough to fill its display area
horizontally, but don't change its height),
GridBagConstraints.VERTICAL
(make the component tall enough to fill its display area
vertically, but don't change its width), and
GridBagConstraints.BOTH
(make the component fill its display area entirely).
GridBagConstraints.ipadx
,
GridBagConstraints.ipady
ipadx pixels. Similarly, the height of
the component will be at least the minimum height plus
ipady pixels.
GridBagConstraints.insets
GridBagConstraints.anchor
ComponentOrientation property while absolute values
are not. Valid values are:
Absolute Values |
Relative Values |
|---|---|
GridBagConstraints.NORTHGridBagConstraints.SOUTHGridBagConstraints.WESTGridBagConstraints.EASTGridBagConstraints.NORTHWESTGridBagConstraints.NORTHEASTGridBagConstraints.SOUTHWESTGridBagConstraints.SOUTHEASTGridBagConstraints.CENTER (the default) |
GridBagConstraints.PAGE_STARTGridBagConstraints.PAGE_ENDGridBagConstraints.LINE_STARTGridBagConstraints.LINE_ENDGridBagConstraints.FIRST_LINE_STARTGridBagConstraints.FIRST_LINE_ENDGridBagConstraints.LAST_LINE_STARTGridBagConstraints.LAST_LINE_END |
GridBagConstraints.weightx
,
GridBagConstraints.weighty
weightx) and column (weighty),
all the components clump together in the center of their container.
This is because when the weight is zero (the default),
the GridBagLayout object puts any extra space
between its grid of cells and the edges of the container.
The following figures show ten components (all buttons) managed by a grid bag layout. Figure 1 shows the layout for a horizontal, left-to-right container and Figure 2 shows the layout for a horizontal, right-to-left container.
|
|
| Figure 1: Horizontal, Left-to-Right | Figure 2: Horizontal, Right-to-Left |
Each of the ten components has the fill field
of its associated GridBagConstraints object
set to GridBagConstraints.BOTH.
In addition, the components have the following non-default constraints:
weightx = 1.0
weightx = 1.0,
gridwidth = GridBagConstraints.REMAINDER
gridwidth = GridBagConstraints.REMAINDER
gridwidth = GridBagConstraints.RELATIVE
gridwidth = GridBagConstraints.REMAINDER
gridheight = 2,
weighty = 1.0
gridwidth = GridBagConstraints.REMAINDER
Here is the code that implements the example shown above:
import java.awt.*;
import java.util.*;
import java.applet.Applet;
public class GridBagEx1 extends Applet {
protected void makebutton(String name,
GridBagLayout gridbag,
GridBagConstraints c) {
Button button = new Button(name);
gridbag.setConstraints(button, c);
add(button);
}
public void init() {
GridBagLayout gridbag = new GridBagLayout();
GridBagConstraints c = new GridBagConstraints();
setFont(new Font("SansSerif", Font.PLAIN, 14));
setLayout(gridbag);
c.fill = GridBagConstraints.BOTH;
c.weightx = 1.0;
makebutton("Button1", gridbag, c);
makebutton("Button2", gridbag, c);
makebutton("Button3", gridbag, c);
c.gridwidth = GridBagConstraints.REMAINDER; //end row
makebutton("Button4", gridbag, c);
c.weightx = 0.0; //reset to the default
makebutton("Button5", gridbag, c); //another row
c.gridwidth = GridBagConstraints.RELATIVE; //next-to-last in row
makebutton("Button6", gridbag, c);
c.gridwidth = GridBagConstraints.REMAINDER; //end row
makebutton("Button7", gridbag, c);
c.gridwidth = 1; //reset to the default
c.gridheight = 2;
c.weighty = 1.0;
makebutton("Button8", gridbag, c);
c.weighty = 0.0; //reset to the default
c.gridwidth = GridBagConstraints.REMAINDER; //end row
c.gridheight = 1; //reset to the default
makebutton("Button9", gridbag, c);
makebutton("Button10", gridbag, c);
setSize(300, 100);
}
public static void main(String args[]) {
Frame f = new Frame("GridBag Layout Example");
GridBagEx1 ex1 = new GridBagEx1();
ex1.init();
f.add("Center", ex1);
f.pack();
f.setSize(f.getPreferredSize());
f.show();
}
}
GridBagConstraints
,
ComponentOrientation
,
Serialized Form| Field Summary | |
|---|---|
double[] |
columnWeights
This field holds the overrides to the column weights. |
int[] |
columnWidths
This field holds the overrides to the column minimum width. |
protected Hashtable |
comptable
This hashtable maintains the association between a component and its gridbag constraints. |
protected GridBagConstraints |
defaultConstraints
This field holds a gridbag constraints instance containing the default values, so if a component does not have gridbag constraints associated with it, then the component will be assigned a copy of the defaultConstraints. |
protected java.awt.GridBagLayoutInfo |
layoutInfo
This field holds the layout information for the gridbag. |
protected static int |
MAXGRIDSIZE
|
protected static int |
MINSIZE
The smallest grid that can be laid out by the grid bag layout. |
protected static int |
PREFERREDSIZE
The preferred grid size that can be laid out by the grid bag layout. |
int[] |
rowHeights
This field holds the overrides to the row minimum heights. |
double[] |
rowWeights
This field holds the overrides to the row weights. |
| Constructor Summary | |
|---|---|
GridBagLayout
Creates a grid bag layout manager. |
|
| Method Summary | |
|---|---|
void |
addLayoutComponent
Adds the specified component to the layout, using the specified constraints object. |
void |
addLayoutComponent
Has no effect, since this layout manager does not use a per-component string. |
protected void |
adjustForGravity
Adjusts the x, y, width, and height fields to the correct values depending on the constraint geometry and pads. |
protected void |
AdjustForGravity
This method is obsolete and supplied for backwards compatability only; new code should call adjustForGravity instead. |
protected void |
arrangeGrid
Lays out the grid. |
protected void |
ArrangeGrid
This method is obsolete and supplied for backwards compatability only; new code should call arrangeGrid instead. |
GridBagConstraints |
getConstraints
Gets the constraints for the specified component. |
float |
getLayoutAlignmentX
Returns the alignment along the x axis. |
float |
getLayoutAlignmentY
Returns the alignment along the y axis. |
int[][] |
getLayoutDimensions
Determines column widths and row heights for the layout grid. |
protected java.awt.GridBagLayoutInfo |
getLayoutInfo
Fills in an instance of GridBagLayoutInfo for the
current set of managed children. |
protected java.awt.GridBagLayoutInfo |
GetLayoutInfo
This method is obsolete and supplied for backwards compatability only; new code should call getLayoutInfo instead. |
Point |
getLayoutOrigin
Determines the origin of the layout area, in the graphics coordinate space of the target container. |
double[][] |
getLayoutWeights
Determines the weights of the layout grid's columns and rows. |
protected Dimension |
getMinSize
Figures out the minimum size of the master based on the information from getLayoutInfo. |
protected Dimension |
GetMinSize
This method is obsolete and supplied for backwards compatability only; new code should call getMinSize instead. |
void |
invalidateLayout
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded. |
void |
layoutContainer
Lays out the specified container using this grid bag layout. |
Point |
location
Determines which cell in the layout grid contains the point specified by (x, y). |
protected GridBagConstraints |
lookupConstraints
Retrieves the constraints for the specified component. |
Dimension |
maximumLayoutSize
Returns the maximum dimensions for this layout given the components in the specified target container. |
Dimension |
minimumLayoutSize
Determines the minimum size of the parent container
using this grid bag layout. |
Dimension |
preferredLayoutSize
Determines the preferred size of the parent
container using this grid bag layout. |
void |
removeLayoutComponent
Removes the specified component from this layout. |
void |
setConstraints
Sets the constraints for the specified component in this layout. |
String |
toString
Returns a string representation of this grid bag layout's values. |
Methods inherited from class java.lang.Object ![]() |
|---|
clone |
| Field Detail |
|---|

protected static final int MAXGRIDSIZE

protected static final int MINSIZE

protected static final int PREFERREDSIZE

protected Hashtable![]()
![]()
<Component
![]()
![]()
,GridBagConstraints
![]()
![]()
> comptable
comptable are the components and the
values are the instances of GridBagConstraints.
GridBagConstraints


protected GridBagConstraints![]()
![]()
defaultConstraints
defaultConstraints.
getConstraints(Component)
,
setConstraints(Component, GridBagConstraints)
,
lookupConstraints(Component)


protected java.awt.GridBagLayoutInfo layoutInfo
layoutInfo is null
this indicates that there are no components in
the gridbag or if there are components, they have
not yet been validated.
getLayoutInfo(Container, int)


public int[] columnWidths
null the values are
applied to the gridbag after all of the minimum columns
widths have been calculated.
If columnWidths has more elements than the number of
columns, columns are added to the gridbag to match
the number of elements in columnWidth.
getLayoutDimensions()


public int[] rowHeights
rowHeights has more elements than the number of
rows, rowa are added to the gridbag to match
the number of elements in rowHeights.
getLayoutDimensions()


public double[] columnWeights
null the values are
applied to the gridbag after all of the columns
weights have been calculated.
If columnWeights[i] > weight for column i, then
column i is assigned the weight in columnWeights[i].
If columnWeights has more elements than the number
of columns, the excess elements are ignored - they do
not cause more columns to be created.

public double[] rowWeights
rowWeights[i] > weight for row i, then
row i is assigned the weight in rowWeights[i].
If rowWeights has more elements than the number
of rows, the excess elements are ignored - they do
not cause more rows to be created.
| Constructor Detail |
|---|

public GridBagLayout()
| Method Detail |
|---|

public void setConstraints(Component![]()
![]()
comp, GridBagConstraints
![]()
![]()
constraints)
comp - the component to be modifiedconstraints - the constraints to be applied

public GridBagConstraints![]()
![]()
getConstraints(Component
![]()
![]()
comp)
GridBagConstraints object is returned.
comp - the component to be queried

protected GridBagConstraints![]()
![]()
lookupConstraints(Component
![]()
![]()
comp)
GridBagConstraints object used by the layout mechanism.
If comp is not in the GridBagLayout,
a set of default GridBagConstraints are returned.
A comp value of null is invalid
and returns null.
comp - the component to be queried

public Point![]()
![]()
getLayoutOrigin()
ComponentOrientation value of the container. This
is distinct from the grid origin given by the cell coordinates (0,0).
Most applications do not call this method directly.
ComponentOrientation


public int[][] getLayoutDimensions()
Most applications do not call this method directly.

public double[][] getLayoutWeights()
Most applications do not call this method directly.

public Point![]()
![]()
location(int x, int y)
(x, y). 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).
If the (x, y) point lies
outside the grid, the following rules are used.
The column index is returned as zero if x lies to the
left of the layout for a left-to-right container or to the right of
the layout for a right-to-left container. The column index is returned
as the number of columns if x lies
to the right of the layout in a left-to-right container or to the left
in a right-to-left container.
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. The orientation of a container is determined by its
ComponentOrientation property.
x - the x coordinate of a pointy - the y coordinate of a point
ComponentOrientation


public void addLayoutComponent(String![]()
![]()
name, Component
![]()
![]()
comp)
addLayoutComponent

in interface LayoutManager

name - the string to be associated with the componentcomp - the component to be added

public void addLayoutComponent(Component![]()
![]()
comp, Object
![]()
![]()
constraints)
constraints object. Note that constraints
are mutable and are, therefore, cloned when cached.
addLayoutComponent

in interface LayoutManager2

comp - the component to be addedconstraints - an object that determines how
the component is added to the layout
IllegalArgumentException

- if constraints
is not a GridBagConstraint

public void removeLayoutComponent(Component![]()
![]()
comp)
Most applications do not call this method directly.
removeLayoutComponent

in interface LayoutManager

comp - the component to be removed.Container.remove(java.awt.Component)
,
Container.removeAll()


public Dimension![]()
![]()
preferredLayoutSize(Container
![]()
![]()
parent)
parent
container using this grid bag layout.
Most applications do not call this method directly.
preferredLayoutSize

in interface LayoutManager

parent - the container in which to do the layout
parent
containerContainer.getPreferredSize()


public Dimension![]()
![]()
minimumLayoutSize(Container
![]()
![]()
parent)
parent container
using this grid bag layout.
Most applications do not call this method directly.
minimumLayoutSize

in interface LayoutManager

parent - the container in which to do the layout
parent containerContainer.doLayout()


public Dimension![]()
![]()
maximumLayoutSize(Container
![]()
![]()
target)
maximumLayoutSize

in interface LayoutManager2

target - the container which needs to be laid out
Container
,
minimumLayoutSize(Container)
,
preferredLayoutSize(Container)


public float getLayoutAlignmentX(Container![]()
![]()
parent)
getLayoutAlignmentX

in interface LayoutManager2

0.5f to indicate centered

public float getLayoutAlignmentY(Container![]()
![]()
parent)
getLayoutAlignmentY

in interface LayoutManager2

0.5f to indicate centered

public void invalidateLayout(Container![]()
![]()
target)
invalidateLayout

in interface LayoutManager2


public void layoutContainer(Container![]()
![]()
parent)
GridBagLayout
object.
Most applications do not call this method directly.
layoutContainer

in interface LayoutManager

parent - the container in which to do the layoutContainer
,
Container.doLayout()


public String![]()
![]()
toString()
toString

in class Object


protected java.awt.GridBagLayoutInfo getLayoutInfo(Container![]()
![]()
parent, int sizeflag)
GridBagLayoutInfo for the
current set of managed children. This requires three passes through the
set of children:
This method should only be used internally by
GridBagLayout.
parent - the layout containersizeflag - either PREFERREDSIZE or
MINSIZE
GridBagLayoutInfo for the set of children

protected java.awt.GridBagLayoutInfo GetLayoutInfo(Container![]()
![]()
parent, int sizeflag)
getLayoutInfo
instead.
This method is the same as getLayoutInfo;
refer to getLayoutInfo for details on parameters
and return value.

protected void adjustForGravity(GridBagConstraints![]()
![]()
constraints, Rectangle
![]()
![]()
r)
GridBagLayout.
constraints - the constraints to be appliedr - the Rectangle to be adjusted

protected void AdjustForGravity(GridBagConstraints![]()
![]()
constraints, Rectangle
![]()
![]()
r)
adjustForGravity
instead.
This method is the same as adjustForGravity;
refer to adjustForGravity for details
on parameters.

protected Dimension![]()
![]()
getMinSize(Container
![]()
![]()
parent, java.awt.GridBagLayoutInfo info)
getLayoutInfo.
This method should only be used internally by
GridBagLayout.
parent - the layout containerinfo - the layout info for this parent
Dimension object containing the
minimum size

protected Dimension![]()
![]()
GetMinSize(Container
![]()
![]()
parent, java.awt.GridBagLayoutInfo info)
getMinSize
instead.
This method is the same as getMinSize;
refer to getMinSize for details on parameters
and return value.

protected void arrangeGrid(Container![]()
![]()
parent)
GridBagLayout.
parent - the layout container

protected void ArrangeGrid(Container![]()
![]()
parent)
arrangeGrid
instead.
This method is the same as arrangeGrid;
refer to arrangeGrid for details on the
parameter.
|
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| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||