Class GroupLayout
- java.lang.Object
-
- javax.swing.GroupLayout
- All Implemented Interfaces:
-
LayoutManager
,LayoutManager2
public class GroupLayout extends Object implements LayoutManager2
GroupLayout
is a LayoutManager
that hierarchically groups components in order to position them in a Container
. GroupLayout
is intended for use by builders, but may be hand-coded as well. Grouping is done by instances of the Group
class.
GroupLayout
supports two types of groups. A sequential group positions its child elements sequentially, one after another. A parallel group aligns its child elements in one of four ways.
Each group may contain any number of elements, where an element is a Group
, Component
, or gap. A gap can be thought of as an invisible component with a minimum, preferred and maximum size. In addition GroupLayout
supports a preferred gap, whose value comes from LayoutStyle
.
Elements are similar to a spring. Each element has a range as specified by a minimum, preferred and maximum. Gaps have either a developer-specified range, or a range determined by
LayoutStyle
. The range for Component
s is determined from the Component
's getMinimumSize
,
getPreferredSize
and getMaximumSize
methods. In addition, when adding Component
s you may specify a particular range to use instead of that from the component. The range for a
Group
is determined by the type of group. A ParallelGroup
's range is the maximum of the ranges of its elements. A
SequentialGroup
's range is the sum of the ranges of its elements.
GroupLayout
treats each axis independently. That is, there is a group representing the horizontal axis, and a group representing the vertical axis. The horizontal group is responsible for determining the minimum, preferred and maximum size along the horizontal axis as well as setting the x and width of the components contained in it. The vertical group is responsible for determining the minimum, preferred and maximum size along the vertical axis as well as setting the y and height of the components contained in it. Each Component
must exist in both a horizontal and vertical group, otherwise an IllegalStateException
is thrown during layout, or when the minimum, preferred or maximum size is requested.
The following diagram shows a sequential group along the horizontal axis. The sequential group contains three components. A parallel group was used along the vertical axis.
To reinforce that each axis is treated independently the diagram shows the range of each group and element along each axis. The range of each component has been projected onto the axes, and the groups are rendered in blue (horizontal) and red (vertical). For readability there is a gap between each of the elements in the sequential group.
The sequential group along the horizontal axis is rendered as a solid blue line. Notice the sequential group is the sum of the children elements it contains.
Along the vertical axis the parallel group is the maximum of the height of each of the components. As all three components have the same height, the parallel group has the same height.
The following diagram shows the same three components, but with the parallel group along the horizontal axis and the sequential group along the vertical axis.
As c1
is the largest of the three components, the parallel group is sized to c1
. As c2
and c3
are smaller than c1
they are aligned based on the alignment specified for the component (if specified) or the default alignment of the parallel group. In the diagram c2
and c3
were created with an alignment of LEADING
. If the component orientation were right-to-left then c2
and c3
would be positioned on the opposite side.
The following diagram shows a sequential group along both the horizontal and vertical axis.
GroupLayout
provides the ability to insert gaps between Component
s. The size of the gap is determined by an instance of LayoutStyle
. This may be turned on using the setAutoCreateGaps
method. Similarly, you may use the setAutoCreateContainerGaps
method to insert gaps between components that touch the edge of the parent container and the container.
The following builds a panel consisting of two labels in one column, followed by two textfields in the next column:
JComponent panel = ...; GroupLayout layout = new GroupLayout(panel); panel.setLayout(layout); // Turn on automatically adding gaps between components layout.setAutoCreateGaps(true); // Turn on automatically creating gaps between components that touch // the edge of the container and the container. layout.setAutoCreateContainerGaps(true); // Create a sequential group for the horizontal axis. GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup(); // The sequential group in turn contains two parallel groups. // One parallel group contains the labels, the other the text fields. // Putting the labels in a parallel group along the horizontal axis // positions them at the same x location. // // Variable indentation is used to reinforce the level of grouping. hGroup.addGroup(layout.createParallelGroup(). addComponent(label1).addComponent(label2)); hGroup.addGroup(layout.createParallelGroup(). addComponent(tf1).addComponent(tf2)); layout.setHorizontalGroup(hGroup); // Create a sequential group for the vertical axis. GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup(); // The sequential group contains two parallel groups that align // the contents along the baseline. The first parallel group contains // the first label and text field, and the second parallel group contains // the second label and text field. By using a sequential group // the labels and text fields are positioned vertically after one another. vGroup.addGroup(layout.createParallelGroup(Alignment.BASELINE). addComponent(label1).addComponent(tf1)); vGroup.addGroup(layout.createParallelGroup(Alignment.BASELINE). addComponent(label2).addComponent(tf2)); layout.setVerticalGroup(vGroup);
When run the following is produced.
This layout consists of the following.
- The horizontal axis consists of a sequential group containing two parallel groups. The first parallel group contains the labels, and the second parallel group contains the text fields.
- The vertical axis consists of a sequential group containing two parallel groups. The parallel groups are configured to align their components along the baseline. The first parallel group contains the first label and first text field, and the second group consists of the second label and second text field.
- You need not explicitly add the components to the container; this is indirectly done by using one of the
add
methods ofGroup
. - The various
add
methods return the caller. This allows for easy chaining of invocations. For example,group.addComponent(label1).addComponent(label2);
is equivalent togroup.addComponent(label1); group.addComponent(label2);
. - There are no public constructors for
Group
s; instead use the create methods ofGroupLayout
.
- Since:
- 1.6
Nested Class Summary
Modifier and Type | Class | Description |
---|---|---|
static class | GroupLayout.Alignment | Enumeration of the possible ways |
class | GroupLayout.Group |
|
class | GroupLayout.ParallelGroup | A |
class | GroupLayout.SequentialGroup | A |
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static int | DEFAULT_SIZE | Indicates the size from the component or gap should be used for a particular range value. |
static int | PREFERRED_SIZE | Indicates the preferred size from the component or gap should be used for a particular range value. |
Constructor Summary
Constructor | Description |
---|---|
GroupLayout(Container host) | Creates a |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | addLayoutComponent(Component component,
Object constraints) | Notification that a |
void | addLayoutComponent(String name,
Component component) | Notification that a |
GroupLayout.ParallelGroup | createBaselineGroup(boolean resizable,
boolean anchorBaselineToTop) | Creates and returns a |
GroupLayout.ParallelGroup | createParallelGroup() | Creates and returns a |
GroupLayout.ParallelGroup | createParallelGroup(GroupLayout.Alignment alignment) | Creates and returns a |
GroupLayout.ParallelGroup | createParallelGroup(GroupLayout.Alignment alignment,
boolean resizable) | Creates and returns a |
GroupLayout.SequentialGroup | createSequentialGroup() | Creates and returns a |
boolean | getAutoCreateContainerGaps() | Returns |
boolean | getAutoCreateGaps() | Returns |
boolean | getHonorsVisibility() | Returns whether component visibility is considered when sizing and positioning components. |
float | getLayoutAlignmentX(Container parent) | Returns the alignment along the x axis. |
float | getLayoutAlignmentY(Container parent) | Returns the alignment along the y axis. |
LayoutStyle | getLayoutStyle() | Returns the |
void | invalidateLayout(Container parent) | Invalidates the layout, indicating that if the layout manager has cached information it should be discarded. |
void | layoutContainer(Container parent) | Lays out the specified container. |
void | linkSize(int axis,
Component... components) | Forces the specified components to have the same size along the specified axis regardless of their preferred, minimum or maximum sizes. |
void | linkSize(Component... components) | Forces the specified components to have the same size regardless of their preferred, minimum or maximum sizes. |
Dimension | maximumLayoutSize(Container parent) | Returns the maximum size for the specified container. |
Dimension | minimumLayoutSize(Container parent) | Returns the minimum size for the specified container. |
Dimension | preferredLayoutSize(Container parent) | Returns the preferred size for the specified container. |
void | removeLayoutComponent(Component component) | Notification that a |
void | replace(Component existingComponent,
Component newComponent) | Replaces an existing component with a new one. |
void | setAutoCreateContainerGaps(boolean autoCreateContainerPadding) | Sets whether a gap between the container and components that touch the border of the container should automatically be created. |
void | setAutoCreateGaps(boolean autoCreatePadding) | Sets whether a gap between components should automatically be created. |
void | setHonorsVisibility(boolean honorsVisibility) | Sets whether component visibility is considered when sizing and positioning components. |
void | setHonorsVisibility(Component component,
Boolean honorsVisibility) | Sets whether the component's visibility is considered for sizing and positioning. |
void | setHorizontalGroup(GroupLayout.Group group) | Sets the |
void | setLayoutStyle(LayoutStyle layoutStyle) | Sets the |
void | setVerticalGroup(GroupLayout.Group group) | Sets the |
String | toString() | Returns a string representation of this |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Field Detail
DEFAULT_SIZE
public static final int DEFAULT_SIZE
Indicates the size from the component or gap should be used for a particular range value.
- See Also:
-
GroupLayout.Group
, Constant Field Values
PREFERRED_SIZE
public static final int PREFERRED_SIZE
Indicates the preferred size from the component or gap should be used for a particular range value.
- See Also:
-
GroupLayout.Group
, Constant Field Values
Constructor Detail
GroupLayout
public GroupLayout(Container host)
Creates a GroupLayout
for the specified Container
.
- Parameters:
-
host
- theContainer
theGroupLayout
is theLayoutManager
for - Throws:
-
IllegalArgumentException
- if host isnull
Method Detail
setHonorsVisibility
public void setHonorsVisibility(boolean honorsVisibility)
Sets whether component visibility is considered when sizing and positioning components. A value of true
indicates that non-visible components should not be treated as part of the layout. A value of false
indicates that components should be positioned and sized regardless of visibility.
A value of false
is useful when the visibility of components is dynamically adjusted and you don't want surrounding components and the sizing to change.
The specified value is used for components that do not have an explicit visibility specified.
The default is true
.
- Parameters:
-
honorsVisibility
- whether component visibility is considered when sizing and positioning components - See Also:
setHonorsVisibility(Component,Boolean)
getHonorsVisibility
public boolean getHonorsVisibility()
Returns whether component visibility is considered when sizing and positioning components.
- Returns:
- whether component visibility is considered when sizing and positioning components
setHonorsVisibility
public void setHonorsVisibility(Component component, Boolean honorsVisibility)
Sets whether the component's visibility is considered for sizing and positioning. A value of Boolean.TRUE
indicates that if component
is not visible it should not be treated as part of the layout. A value of false
indicates that component
is positioned and sized regardless of it's visibility. A value of null
indicates the value specified by the single argument method
setHonorsVisibility
should be used.
If component
is not a child of the Container
this GroupLayout
is managing, it will be added to the Container
.
- Parameters:
-
component
- the component -
honorsVisibility
- whether visibility of thiscomponent
should be considered for sizing and positioning - Throws:
-
IllegalArgumentException
- ifcomponent
isnull
- See Also:
setHonorsVisibility(Component,Boolean)
setAutoCreateGaps
public void setAutoCreateGaps(boolean autoCreatePadding)
Sets whether a gap between components should automatically be created. For example, if this is true
and you add two components to a SequentialGroup
a gap between the two components is automatically be created. The default is false
.
- Parameters:
-
autoCreatePadding
- whether a gap between components is automatically created
getAutoCreateGaps
public boolean getAutoCreateGaps()
Returns true
if gaps between components are automatically created.
- Returns:
-
true
if gaps between components are automatically created
setAutoCreateContainerGaps
public void setAutoCreateContainerGaps(boolean autoCreateContainerPadding)
Sets whether a gap between the container and components that touch the border of the container should automatically be created. The default is false
.
- Parameters:
-
autoCreateContainerPadding
- whether a gap between the container and components that touch the border of the container should automatically be created
getAutoCreateContainerGaps
public boolean getAutoCreateContainerGaps()
Returns true
if gaps between the container and components that border the container are automatically created.
- Returns:
-
true
if gaps between the container and components that border the container are automatically created
setHorizontalGroup
public void setHorizontalGroup(GroupLayout.Group group)
Sets the Group
that positions and sizes components along the horizontal axis.
- Parameters:
-
group
- theGroup
that positions and sizes components along the horizontal axis - Throws:
-
IllegalArgumentException
- if group isnull
setVerticalGroup
public void setVerticalGroup(GroupLayout.Group group)
Sets the Group
that positions and sizes components along the vertical axis.
- Parameters:
-
group
- theGroup
that positions and sizes components along the vertical axis - Throws:
-
IllegalArgumentException
- if group isnull
createSequentialGroup
public GroupLayout.SequentialGroup createSequentialGroup()
Creates and returns a SequentialGroup
.
- Returns:
- a new
SequentialGroup
createParallelGroup
public GroupLayout.ParallelGroup createParallelGroup()
Creates and returns a ParallelGroup
with an alignment of Alignment.LEADING
. This is a cover method for the more general createParallelGroup(Alignment)
method.
- Returns:
- a new
ParallelGroup
- See Also:
createParallelGroup(Alignment)
createParallelGroup
public GroupLayout.ParallelGroup createParallelGroup(GroupLayout.Alignment alignment)
Creates and returns a ParallelGroup
with the specified alignment. This is a cover method for the more general
createParallelGroup(Alignment,boolean)
method with true
supplied for the second argument.
- Parameters:
-
alignment
- the alignment for the elements of the group - Returns:
- a new
ParallelGroup
- Throws:
-
IllegalArgumentException
- ifalignment
isnull
- See Also:
-
createBaselineGroup(boolean, boolean)
,GroupLayout.ParallelGroup
createParallelGroup
public GroupLayout.ParallelGroup createParallelGroup(GroupLayout.Alignment alignment, boolean resizable)
Creates and returns a ParallelGroup
with the specified alignment and resize behavior. The
alignment
argument specifies how children elements are positioned that do not fill the group. For example, if a
ParallelGroup
with an alignment of TRAILING
is given 100 and a child only needs 50, the child is positioned at the position 50 (with a component orientation of left-to-right).
Baseline alignment is only useful when used along the vertical axis. A ParallelGroup
created with a baseline alignment along the horizontal axis is treated as LEADING
.
Refer to ParallelGroup
for details on the behavior of baseline groups.
- Parameters:
-
alignment
- the alignment for the elements of the group -
resizable
-true
if the group is resizable; if the group is not resizable the preferred size is used for the minimum and maximum size of the group - Returns:
- a new
ParallelGroup
- Throws:
-
IllegalArgumentException
- ifalignment
isnull
- See Also:
-
createBaselineGroup(boolean, boolean)
,GroupLayout.ParallelGroup
createBaselineGroup
public GroupLayout.ParallelGroup createBaselineGroup(boolean resizable, boolean anchorBaselineToTop)
Creates and returns a ParallelGroup
that aligns it's elements along the baseline.
- Parameters:
-
resizable
- whether the group is resizable -
anchorBaselineToTop
- whether the baseline is anchored to the top or bottom of the group - Returns:
- the
ParallelGroup
- See Also:
-
createBaselineGroup(boolean, boolean)
,GroupLayout.ParallelGroup
linkSize
public void linkSize(Component... components)
Forces the specified components to have the same size regardless of their preferred, minimum or maximum sizes. Components that are linked are given the maximum of the preferred size of each of the linked components. For example, if you link two components with a preferred width of 10 and 20, both components are given a width of 20.
This can be used multiple times to force any number of components to share the same size.
Linked Components are not be resizable.
- Parameters:
-
components
- theComponent
s that are to have the same size - Throws:
-
IllegalArgumentException
- ifcomponents
isnull
, or containsnull
- See Also:
linkSize(int,Component[])
linkSize
public void linkSize(int axis, Component... components)
Forces the specified components to have the same size along the specified axis regardless of their preferred, minimum or maximum sizes. Components that are linked are given the maximum of the preferred size of each of the linked components. For example, if you link two components along the horizontal axis and the preferred width is 10 and 20, both components are given a width of 20.
This can be used multiple times to force any number of components to share the same size.
Linked Component
s are not be resizable.
- Parameters:
-
axis
- the axis to link the size along; one ofSwingConstants.HORIZONTAL
orSwingConstants.VERTICAL
-
components
- theComponent
s that are to have the same size - Throws:
-
IllegalArgumentException
- ifcomponents
isnull
, or containsnull
; oraxis
is notSwingConstants.HORIZONTAL
orSwingConstants.VERTICAL
replace
public void replace(Component existingComponent, Component newComponent)
Replaces an existing component with a new one.
- Parameters:
-
existingComponent
- the component that should be removed and replaced withnewComponent
-
newComponent
- the component to put inexistingComponent
's place - Throws:
-
IllegalArgumentException
- if either of the components arenull
orexistingComponent
is not being managed by this layout manager
setLayoutStyle
public void setLayoutStyle(LayoutStyle layoutStyle)
Sets the LayoutStyle
used to calculate the preferred gaps between components. A value of null
indicates the shared instance of LayoutStyle
should be used.
- Parameters:
-
layoutStyle
- theLayoutStyle
to use - See Also:
LayoutStyle
getLayoutStyle
public LayoutStyle getLayoutStyle()
Returns the LayoutStyle
used for calculating the preferred gap between components. This returns the value specified to setLayoutStyle
, which may be null
.
- Returns:
- the
LayoutStyle
used for calculating the preferred gap between components
addLayoutComponent
public void addLayoutComponent(String name, Component component)
Notification that a Component
has been added to the parent container. You should not invoke this method directly, instead you should use one of the Group
methods to add a Component
.
- Specified by:
-
addLayoutComponent
in interfaceLayoutManager
- Parameters:
-
name
- the string to be associated with the component -
component
- theComponent
to be added
removeLayoutComponent
public void removeLayoutComponent(Component component)
Notification that a Component
has been removed from the parent container. You should not invoke this method directly, instead invoke remove
on the parent Container
.
- Specified by:
-
removeLayoutComponent
in interfaceLayoutManager
- Parameters:
-
component
- the component to be removed - See Also:
Component.remove(java.awt.MenuComponent)
preferredLayoutSize
public Dimension preferredLayoutSize(Container parent)
Returns the preferred size for the specified container.
- Specified by:
-
preferredLayoutSize
in interfaceLayoutManager
- Parameters:
-
parent
- the container to return the preferred size for - Returns:
- the preferred size for
parent
- Throws:
-
IllegalArgumentException
- ifparent
is not the sameContainer
this was created with -
IllegalStateException
- if any of the components added to this layout are not in both a horizontal and vertical group - See Also:
Container.getPreferredSize()
minimumLayoutSize
public Dimension minimumLayoutSize(Container parent)
Returns the minimum size for the specified container.
- Specified by:
-
minimumLayoutSize
in interfaceLayoutManager
- Parameters:
-
parent
- the container to return the size for - Returns:
- the minimum size for
parent
- Throws:
-
IllegalArgumentException
- ifparent
is not the sameContainer
that this was created with -
IllegalStateException
- if any of the components added to this layout are not in both a horizontal and vertical group - See Also:
Container.getMinimumSize()
layoutContainer
public void layoutContainer(Container parent)
Lays out the specified container.
- Specified by:
-
layoutContainer
in interfaceLayoutManager
- Parameters:
-
parent
- the container to be laid out - Throws:
-
IllegalStateException
- if any of the components added to this layout are not in both a horizontal and vertical group
addLayoutComponent
public void addLayoutComponent(Component component, Object constraints)
Notification that a Component
has been added to the parent container. You should not invoke this method directly, instead you should use one of the Group
methods to add a Component
.
- Specified by:
-
addLayoutComponent
in interfaceLayoutManager2
- Parameters:
-
component
- the component added -
constraints
- description of where to place the component
maximumLayoutSize
public Dimension maximumLayoutSize(Container parent)
Returns the maximum size for the specified container.
- Specified by:
-
maximumLayoutSize
in interfaceLayoutManager2
- Parameters:
-
parent
- the container to return the size for - Returns:
- the maximum size for
parent
- Throws:
-
IllegalArgumentException
- ifparent
is not the sameContainer
that this was created with -
IllegalStateException
- if any of the components added to this layout are not in both a horizontal and vertical group - See Also:
Container.getMaximumSize()
getLayoutAlignmentX
public float getLayoutAlignmentX(Container parent)
Returns the alignment along the x axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.
- Specified by:
-
getLayoutAlignmentX
in interfaceLayoutManager2
- Parameters:
-
parent
- theContainer
hosting thisLayoutManager
- Returns:
- the alignment; this implementation returns
.5
- Throws:
-
IllegalArgumentException
- ifparent
is not the sameContainer
that this was created with
getLayoutAlignmentY
public float getLayoutAlignmentY(Container parent)
Returns the alignment along the y axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.
- Specified by:
-
getLayoutAlignmentY
in interfaceLayoutManager2
- Parameters:
-
parent
- theContainer
hosting thisLayoutManager
- Returns:
- alignment; this implementation returns
.5
- Throws:
-
IllegalArgumentException
- ifparent
is not the sameContainer
that this was created with
invalidateLayout
public void invalidateLayout(Container parent)
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.
- Specified by:
-
invalidateLayout
in interfaceLayoutManager2
- Parameters:
-
parent
- theContainer
hosting this LayoutManager - Throws:
-
IllegalArgumentException
- ifparent
is not the sameContainer
that this was created with
toString
public String toString()
Returns a string representation of this GroupLayout
. This method is intended to be used for debugging purposes, and the content and format of the returned string may vary between implementations.