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Java Platform 1.2 Beta 4 |
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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--java.awt.BorderLayout
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 four relative positioning constants,
BEFORE_FIRST_LINE
, AFTER_LAST_LINE
,
BEFORE_LINE_BEGINS
, and AFTER_LINE_ENDS
.
In a container whose ComponentOrientation is set to
ComponentOrientation.LEFT_TO_RIGHT
, these constants map to
NORTH
, SOUTH
, WEST
, and
EAST
, respectively
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.
NOTE: Currently (in JDK 1.2), 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); } }
java.awt.Container.add(String, Component)
,
ComponentOrientation
, Serialized FormField Summary | |
static String | AFTER_LAST_LINE
The component comes after the last line of the layout's content. |
static String | AFTER_LINE_ENDS
The component goes at the end of the line direction for the layout. |
static String | BEFORE_FIRST_LINE
The component comes before the first line of the layout's content. |
static String | BEFORE_LINE_BEGINS
The component goes at the beginning of the line direction for the layout. |
static String | CENTER
The center layout constraint (middle of container). |
static String | EAST
The east layout constraint (right side of container). |
static String | NORTH
The north layout constraint (top of container). |
static String | SOUTH
The south layout constraint (bottom of container). |
static String | WEST
The west layout constraint (left side of container). |
Constructor Summary | |
BorderLayout()
Constructs a new border layout with no gaps between components. |
|
BorderLayout(int hgap,
int vgap)
Constructs a border layout with the specified gaps between components. |
Method Summary | |
void | addLayoutComponent(Component comp,
Object constraints)
Adds the specified component to the layout, using the specified constraint object. |
void | addLayoutComponent(String name,
Component comp)
Deprecated. replaced by addLayoutComponent(Component, Object) . |
int | getHgap()
Returns the horizontal gap between components. |
float | getLayoutAlignmentX(Container parent)
Returns the alignment along the x axis. |
float | getLayoutAlignmentY(Container parent)
Returns the alignment along the y axis. |
int | getVgap()
Returns the vertical gap between components. |
void | invalidateLayout(Container target)
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded. |
void | layoutContainer(Container target)
Lays out the container argument using this border layout. |
Dimension | maximumLayoutSize(Container target)
Returns the maximum dimensions for this layout given the components in the specified target container. |
Dimension | minimumLayoutSize(Container target)
Determines the minimum size of the target container
using this layout manager.
|
Dimension | preferredLayoutSize(Container target)
Determines the preferred size of the target
container using this layout manager, based on the components
in the container.
|
void | removeLayoutComponent(Component comp)
Removes the specified component from this border layout. |
void | setHgap(int hgap)
Sets the horizontal gap between components. |
void | setVgap(int vgap)
Sets the vertical gap between components. |
String | toString()
Returns a string representation of the state of this border layout. |
Methods inherited from class java.lang.Object | |
clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait |
Field Detail |
public static final String NORTH
public static final String SOUTH
public static final String EAST
public static final String WEST
public static final String CENTER
public static final String BEFORE_FIRST_LINE
Component.getComponentOrientation()
public static final String AFTER_LAST_LINE
Component.getComponentOrientation()
public static final String BEFORE_LINE_BEGINS
Component.getComponentOrientation()
public static final String AFTER_LINE_ENDS
Component.getComponentOrientation()
Constructor Detail |
public BorderLayout()
public BorderLayout(int hgap, int vgap)
hgap
and the vertical gap is specified by vgap
.
hgap
- the horizontal gap.
vgap
- the vertical gap.Method Detail |
public int getHgap()
public void setHgap(int hgap)
hgap
- the horizontal gap between componentspublic int getVgap()
public void setVgap(int vgap)
vgap
- the vertical gap between componentspublic void addLayoutComponent(Component comp, Object constraints)
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.
comp
- the component to be added.
constraints
- an object that specifies how and where
the component is added to the layout.Container.add(java.awt.Component, java.lang.Object)
public void addLayoutComponent(String name, Component comp)
addLayoutComponent(Component, Object)
.public void removeLayoutComponent(Component comp)
remove
or
removeAll
methods. Most applications do not call this
method directly.
comp
- the component to be removed.Container.remove(java.awt.Component)
,
Container.removeAll()
public Dimension minimumLayoutSize(Container target)
target
container
using this layout manager.
This method is called when a container calls its
getMinimumSize
method. Most applications do not call
this method directly.
target
- the container in which to do the layout.Container
,
preferredLayoutSize(java.awt.Container)
,
Container.getMinimumSize()
public Dimension preferredLayoutSize(Container target)
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.
target
- the container in which to do the layout.Container
,
minimumLayoutSize(java.awt.Container)
,
Container.getPreferredSize()
public Dimension maximumLayoutSize(Container target)
target
- the component which needs to be laid outContainer
,
minimumLayoutSize(java.awt.Container)
,
preferredLayoutSize(java.awt.Container)
public float getLayoutAlignmentX(Container parent)
public float getLayoutAlignmentY(Container parent)
public void invalidateLayout(Container target)
public void layoutContainer(Container target)
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.
target
- the container in which to do the layout.Container
,
Container.doLayout()
public String toString()
|
Java Platform 1.2 Beta 4 |
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