| java.lang.Object
 java.awt.BorderLayout
| BorderLayout | | public class BorderLayout implements LayoutManager2,java.io.Serializable(Code) | | A border layout lays out a container, arranging and resizing
its components to fit in five regions:
north, south, east, west, and center.
Each region may contain no more than one component, and
is identified by a corresponding constant:
NORTH, SOUTH, EAST,
WEST, and CENTER. When adding a
component to a container with a border layout, use one of these
five constants, for example:
Panel p = new Panel();
p.setLayout(new BorderLayout());
p.add(new Button("Okay"), BorderLayout.SOUTH);
As a convenience, BorderLayout interprets the
absence of a string specification the same as the constant
CENTER:
Panel p2 = new Panel();
p2.setLayout(new BorderLayout());
p2.add(new TextArea()); // Same as p.add(new TextArea(), BorderLayout.CENTER);
In addition, BorderLayout supports the relative
positioning constants, PAGE_START, PAGE_END,
LINE_START, and LINE_END.
In a container whose ComponentOrientation is set to
ComponentOrientation.LEFT_TO_RIGHT, these constants map to
NORTH, SOUTH, WEST, and
EAST, respectively.
For compatibility with previous releases, BorderLayout
also includes the relative positioning constants BEFORE_FIRST_LINE,
AFTER_LAST_LINE, BEFORE_LINE_BEGINS and
AFTER_LINE_ENDS. These are equivalent to
PAGE_START, PAGE_END, LINE_START
and LINE_END respectively. For
consistency with the relative positioning constants used by other
components, the latter constants are preferred.
Mixing both absolute and relative positioning constants can lead to
unpredicable results. If
you use both types, the relative constants will take precedence.
For example, if you add components using both the NORTH
and PAGE_START constants in a container whose
orientation is LEFT_TO_RIGHT, only the
PAGE_START will be layed out.
NOTE: Currently (in the Java 2 platform v1.2),
BorderLayout does not support vertical
orientations. The isVertical setting on the container's
ComponentOrientation is not respected.
The components are laid out according to their
preferred sizes and the constraints of the container's size.
The NORTH and SOUTH components may
be stretched horizontally; the EAST and
WEST components may be stretched vertically;
the CENTER component may stretch both horizontally
and vertically to fill any space left over.
Here is an example of five buttons in an applet laid out using
the BorderLayout layout manager:
The code for this applet is as follows:
import java.awt.*;
import java.applet.Applet;
public class buttonDir extends Applet {
public void init() {
setLayout(new BorderLayout());
add(new Button("North"), BorderLayout.NORTH);
add(new Button("South"), BorderLayout.SOUTH);
add(new Button("East"), BorderLayout.EAST);
add(new Button("West"), BorderLayout.WEST);
add(new Button("Center"), BorderLayout.CENTER);
}
}
version:
1.66, 05/05/07
author:
Arthur van Hoff
See Also: java.awt.Container.add(StringComponent)
See Also: java.awt.ComponentOrientation
since:
JDK1.0 |
| Field Summary | |
| final public static String | AFTER_LAST_LINE
Synonym for PAGE_END. | | final public static String | AFTER_LINE_ENDS
Synonym for LINE_END. | | final public static String | BEFORE_FIRST_LINE
Synonym for PAGE_START. | | final public static String | BEFORE_LINE_BEGINS
Synonym for LINE_START. | | final public static String | CENTER
The center layout constraint (middle of container). | | final public static String | EAST
The east layout constraint (right side of container). | | final public static String | LINE_END
The component goes at the end of the line direction for the
layout. | | final public static String | LINE_START
The component goes at the beginning of the line direction for the
layout. | | final public static String | NORTH
The north layout constraint (top of container). | | final public static String | PAGE_END
The component comes after the last line of the layout's content. | | final public static String | PAGE_START
The component comes before the first line of the layout's content. | | final public static String | SOUTH
The south layout constraint (bottom of container). | | final public static String | WEST
The west layout constraint (left side of container). | | Component | center
Constant to specify components location to be the
center portion of the border layout. | | Component | east
Constant to specify components location to be the
east portion of the border layout. | | Component | firstItem
A relative positioning constant, that can be used instead of
north, south, east, west or center. | | Component | firstLine
A relative positioning constant, that can be used instead of
north, south, east, west or center.
mixing the two types of constants can lead to unpredicable results. | | int | hgap
Constructs a border layout with the horizontal gaps
between components. | | Component | lastItem
A relative positioning constant, that can be used instead of
north, south, east, west or center. | | Component | lastLine
A relative positioning constant, that can be used instead of
north, south, east, west or center. | | Component | north
Constant to specify components location to be the
north portion of the border layout. | | Component | south
Constant to specify components location to be the
south portion of the border layout. | | int | vgap
Constructs a border layout with the vertical gaps
between components. | | Component | west
Constant to specify components location to be the
west portion of the border layout. |
| Constructor Summary | |
| public | BorderLayout()
Constructs a new border layout with
no gaps between components. | | public | BorderLayout(int hgap, int vgap)
Constructs a border layout with the specified gaps
between components. |
| Method Summary | |
| public void | addLayoutComponent(Component comp, Object constraints)
Adds the specified component to the layout, using the specified
constraint object. | | public void | addLayoutComponent(String name, Component comp)
| | public Object | getConstraints(Component comp)
| | public int | getHgap()
Returns the horizontal gap between components. | | public float | getLayoutAlignmentX(Container parent)
Returns the alignment along the x axis. | | public float | getLayoutAlignmentY(Container parent)
Returns the alignment along the y axis. | | public Component | getLayoutComponent(Object constraints)
| | public Component | getLayoutComponent(Container target, Object constraints)
Returns the component that corresponds to the given constraint location
based on the target Container's component orientation.
Components added with the relative constraints PAGE_START,
PAGE_END, LINE_START, and LINE_END
take precedence over components added with the explicit constraints
NORTH, SOUTH, WEST, and EAST.
The Container's component orientation is used to determine the location of components
added with LINE_START and LINE_END.
Parameters:
constraints - the desired absolute position, one of CENTER,NORTH, SOUTH,EAST, WEST
Parameters:
target - the Container used to obtainthe constraint location based on the target Container 's component orientation. | | public int | getVgap()
Returns the vertical gap between components. | | public void | invalidateLayout(Container target)
Invalidates the layout, indicating that if the layout manager
has cached information it should be discarded. | | public void | layoutContainer(Container target)
Lays out the container argument using this border layout.
This method actually reshapes the components in the specified
container in order to satisfy the constraints of this
BorderLayout object. | | public Dimension | maximumLayoutSize(Container target)
Returns the maximum dimensions for this layout given the components
in the specified target container. | | public Dimension | minimumLayoutSize(Container target)
Determines the minimum size of the target container
using this layout manager.
This method is called when a container calls its
getMinimumSize method. | | public Dimension | preferredLayoutSize(Container target)
Determines the preferred size of the target
container using this layout manager, based on the components
in the container.
Most applications do not call this method directly. | | public void | removeLayoutComponent(Component comp)
Removes the specified component from this border layout. | | public void | setHgap(int hgap)
Sets the horizontal gap between components. | | public void | setVgap(int vgap)
Sets the vertical gap between components. | | public String | toString()
Returns a string representation of the state of this border layout. |
| AFTER_LAST_LINE | | final public static String AFTER_LAST_LINE(Code) | | Synonym for PAGE_END. Exists for compatibility with previous
versions. PAGE_END is preferred.
See Also: BorderLayout.PAGE_END
since:
1.2 |
| AFTER_LINE_ENDS | | final public static String AFTER_LINE_ENDS(Code) | | Synonym for LINE_END. Exists for compatibility with previous
versions. LINE_END is preferred.
See Also: BorderLayout.LINE_END
since:
1.2 |
| BEFORE_FIRST_LINE | | final public static String BEFORE_FIRST_LINE(Code) | | Synonym for PAGE_START. Exists for compatibility with previous
versions. PAGE_START is preferred.
See Also: BorderLayout.PAGE_START
since:
1.2 |
| BEFORE_LINE_BEGINS | | final public static String BEFORE_LINE_BEGINS(Code) | | Synonym for LINE_START. Exists for compatibility with previous
versions. LINE_START is preferred.
See Also: BorderLayout.LINE_START
since:
1.2 |
| CENTER | | final public static String CENTER(Code) | | The center layout constraint (middle of container).
|
| EAST | | final public static String EAST(Code) | | The east layout constraint (right side of container).
|
| LINE_START | | final public static String LINE_START(Code) | | The component goes at the beginning of the line direction for the
layout. For Western, left-to-right and top-to-bottom orientations,
this is equivalent to WEST.
See Also: java.awt.Component.getComponentOrientation
since:
1.4 |
| NORTH | | final public static String NORTH(Code) | | The north layout constraint (top of container).
|
| PAGE_START | | final public static String PAGE_START(Code) | | The component comes before the first line of the layout's content.
For Western, left-to-right and top-to-bottom orientations, this is
equivalent to NORTH.
See Also: java.awt.Component.getComponentOrientation
since:
1.4 |
| SOUTH | | final public static String SOUTH(Code) | | The south layout constraint (bottom of container).
|
| WEST | | final public static String WEST(Code) | | The west layout constraint (left side of container).
|
| firstItem | | Component firstItem(Code) | | A relative positioning constant, that can be used instead of
north, south, east, west or center.
Please read Description for firstLine.
|
| firstLine | | Component firstLine(Code) | | A relative positioning constant, that can be used instead of
north, south, east, west or center.
mixing the two types of constants can lead to unpredicable results. If
you use both types, the relative constants will take precedence.
For example, if you add components using both the NORTH
and BEFORE_FIRST_LINE constants in a container whose
orientation is LEFT_TO_RIGHT, only the
BEFORE_FIRST_LINE will be layed out.
This will be the same for lastLine, firstItem, lastItem.
|
| lastItem | | Component lastItem(Code) | | A relative positioning constant, that can be used instead of
north, south, east, west or center.
Please read Description for firstLine.
|
| lastLine | | Component lastLine(Code) | | A relative positioning constant, that can be used instead of
north, south, east, west or center.
Please read Description for firstLine.
|
| BorderLayout | | public BorderLayout()(Code) | | Constructs a new border layout with
no gaps between components.
|
| BorderLayout | | public BorderLayout(int hgap, int vgap)(Code) | | Constructs a border layout with the specified gaps
between components.
The horizontal gap is specified by hgap
and the vertical gap is specified by vgap.
Parameters:
hgap - the horizontal gap.
Parameters:
vgap - the vertical gap. |
| addLayoutComponent | | public void addLayoutComponent(Component comp, Object constraints)(Code) | | Adds the specified component to the layout, using the specified
constraint object. For border layouts, the constraint must be
one of the following constants: NORTH,
SOUTH, EAST,
WEST, or CENTER.
Most applications do not call this method directly. This method
is called when a component is added to a container using the
Container.add method with the same argument types.
Parameters:
comp - the component to be added.
Parameters:
constraints - an object that specifies how and wherethe component is added to the layout.
See Also: java.awt.Container.add(java.awt.Componentjava.lang.Object)
exception:
IllegalArgumentException - if the constraint object is nota string, or if it not one of the five specifiedconstants.
since:
JDK1.1 |
| getHgap | | public int getHgap()(Code) | | Returns the horizontal gap between components.
since:
JDK1.1 |
| getLayoutAlignmentX | | public float getLayoutAlignmentX(Container parent)(Code) | | 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.
|
| getLayoutAlignmentY | | public float getLayoutAlignmentY(Container parent)(Code) | | 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.
|
| getLayoutComponent | | public Component getLayoutComponent(Object constraints)(Code) | | Gets the component that was added using the given constraint
Parameters:
constraints - the desired constraint, one of CENTER,NORTH, SOUTH,WEST, EAST,PAGE_START, PAGE_END,LINE_START, LINE_END the component at the given location, or null ifthe location is empty
exception:
IllegalArgumentException - if the constraint object isnot one of the nine specified constants
See Also: BorderLayout.addLayoutComponent(java.awt.Component,java.lang.Object)
since:
1.5 |
| getLayoutComponent | | public Component getLayoutComponent(Container target, Object constraints)(Code) | | Returns the component that corresponds to the given constraint location
based on the target Container's component orientation.
Components added with the relative constraints PAGE_START,
PAGE_END, LINE_START, and LINE_END
take precedence over components added with the explicit constraints
NORTH, SOUTH, WEST, and EAST.
The Container's component orientation is used to determine the location of components
added with LINE_START and LINE_END.
Parameters:
constraints - the desired absolute position, one of CENTER,NORTH, SOUTH,EAST, WEST
Parameters:
target - the Container used to obtainthe constraint location based on the target Container 's component orientation. the component at the given location, or null ifthe location is empty
exception:
IllegalArgumentException - if the constraint object isnot one of the five specified constants
exception:
NullPointerException - if the target parameter is null
See Also: BorderLayout.addLayoutComponent(java.awt.Component,java.lang.Object)
since:
1.5 |
| getVgap | | public int getVgap()(Code) | | Returns the vertical gap between components.
since:
JDK1.1 |
| invalidateLayout | | public void invalidateLayout(Container target)(Code) | | Invalidates the layout, indicating that if the layout manager
has cached information it should be discarded.
|
| layoutContainer | | public void layoutContainer(Container target)(Code) | | Lays out the container argument using this border layout.
This method actually reshapes the components in the specified
container in order to satisfy the constraints of this
BorderLayout object. The NORTH
and SOUTH components, if any, are placed at
the top and bottom of the container, respectively. The
WEST and EAST components are
then placed on the left and right, respectively. Finally,
the CENTER object is placed in any remaining
space in the middle.
Most applications do not call this method directly. This method
is called when a container calls its doLayout method.
Parameters:
target - the container in which to do the layout.
See Also: java.awt.Container
See Also: java.awt.Container.doLayout |
| preferredLayoutSize | | public Dimension preferredLayoutSize(Container target)(Code) | | Determines the preferred size of the target
container using this layout manager, based on the components
in the container.
Most applications do not call this method directly. This method
is called when a container calls its getPreferredSize
method.
Parameters:
target - the container in which to do the layout. the preferred dimensions to lay out the subcomponentsof the specified container.
See Also: java.awt.Container
See Also: java.awt.BorderLayout.minimumLayoutSize
See Also: java.awt.Container.getPreferredSize |
| setHgap | | public void setHgap(int hgap)(Code) | | Sets the horizontal gap between components.
Parameters:
hgap - the horizontal gap between components
since:
JDK1.1 |
| setVgap | | public void setVgap(int vgap)(Code) | | Sets the vertical gap between components.
Parameters:
vgap - the vertical gap between components
since:
JDK1.1 |
| toString | | public String toString()(Code) | | Returns a string representation of the state of this border layout.
a string representation of this border layout. |
|
|