Class BorderLayout
- All Implemented Interfaces:
LayoutManager,LayoutManager2,Serializable
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
unpredictable 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 laid out.
NOTE: Currently,
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);
}
}
- Since:
- 1.0
- See Also:
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final StringSynonym for PAGE_END.static final StringSynonym for LINE_END.static final StringSynonym for PAGE_START.static final StringSynonym for LINE_START.static final StringThe center layout constraint (middle of container).static final StringThe east layout constraint (right side of container).static final StringThe component goes at the end of the line direction for the layout.static final StringThe component goes at the beginning of the line direction for the layout.static final StringThe north layout constraint (top of container).static final StringThe component comes after the last line of the layout's content.static final StringThe component comes before the first line of the layout's content.static final StringThe south layout constraint (bottom of container).static final StringThe west layout constraint (left side of container). -
Constructor Summary
ConstructorsConstructorDescriptionConstructs 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
Modifier and TypeMethodDescriptionvoidaddLayoutComponent(Component comp, Object constraints) Adds the specified component to the layout, using the specified constraint object.voidaddLayoutComponent(String name, Component comp) Deprecated.getConstraints(Component comp) Gets the constraints for the specified componentintgetHgap()Returns the horizontal gap between components.floatgetLayoutAlignmentX(Container parent) Returns the alignment along the x axis.floatgetLayoutAlignmentY(Container parent) Returns the alignment along the y axis.getLayoutComponent(Container target, Object constraints) Returns the component that corresponds to the given constraint location based on the targetContainer's component orientation.getLayoutComponent(Object constraints) Gets the component that was added using the given constraintintgetVgap()Returns the vertical gap between components.voidinvalidateLayout(Container target) Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.voidlayoutContainer(Container target) Lays out the container argument using this border layout.maximumLayoutSize(Container target) Returns the maximum dimensions for this layout given the components in the specified target container.minimumLayoutSize(Container target) Determines the minimum size of thetargetcontainer using this layout manager.preferredLayoutSize(Container target) Determines the preferred size of thetargetcontainer using this layout manager, based on the components in the container.voidRemoves the specified component from this border layout.voidsetHgap(int hgap) Sets the horizontal gap between components.voidsetVgap(int vgap) Sets the vertical gap between components.toString()Returns a string representation of the state of this border layout.
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Field Details
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NORTH
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SOUTH
-
EAST
-
WEST
-
CENTER
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BEFORE_FIRST_LINE
Synonym for PAGE_START. Exists for compatibility with previous versions. PAGE_START is preferred.- Since:
- 1.2
- See Also:
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AFTER_LAST_LINE
Synonym for PAGE_END. Exists for compatibility with previous versions. PAGE_END is preferred.- Since:
- 1.2
- See Also:
-
BEFORE_LINE_BEGINS
Synonym for LINE_START. Exists for compatibility with previous versions. LINE_START is preferred.- Since:
- 1.2
- See Also:
-
AFTER_LINE_ENDS
Synonym for LINE_END. Exists for compatibility with previous versions. LINE_END is preferred.- Since:
- 1.2
- See Also:
-
PAGE_START
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.- Since:
- 1.4
- See Also:
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PAGE_END
The component comes after the last line of the layout's content. For Western, left-to-right and top-to-bottom orientations, this is equivalent to SOUTH.- Since:
- 1.4
- See Also:
-
LINE_START
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.- Since:
- 1.4
- See Also:
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LINE_END
The component goes at the end of the line direction for the layout. For Western, left-to-right and top-to-bottom orientations, this is equivalent to EAST.- Since:
- 1.4
- See Also:
-
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Constructor Details
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BorderLayout
public BorderLayout()Constructs a new border layout with no gaps between components. -
BorderLayout
public BorderLayout(int hgap, int vgap) Constructs a border layout with the specified gaps between components. The horizontal gap is specified byhgapand the vertical gap is specified byvgap.- Parameters:
hgap- the horizontal gap.vgap- the vertical gap.
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Method Details
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getHgap
public int getHgap()Returns the horizontal gap between components.- Returns:
- the horizontal gap between components
- Since:
- 1.1
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setHgap
public void setHgap(int hgap) Sets the horizontal gap between components.- Parameters:
hgap- the horizontal gap between components- Since:
- 1.1
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getVgap
public int getVgap()Returns the vertical gap between components.- Returns:
- the vertical gap between components
- Since:
- 1.1
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setVgap
public void setVgap(int vgap) Sets the vertical gap between components.- Parameters:
vgap- the vertical gap between components- Since:
- 1.1
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addLayoutComponent
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, orCENTER.Most applications do not call this method directly. This method is called when a component is added to a container using the
Container.addmethod with the same argument types.- Specified by:
addLayoutComponentin interfaceLayoutManager2- Parameters:
comp- the component to be added.constraints- an object that specifies how and where the component is added to the layout.- Throws:
IllegalArgumentException- if the constraint object is not a string, or if it not one of the five specified constants.- Since:
- 1.1
- See Also:
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addLayoutComponent
Deprecated.replaced byaddLayoutComponent(Component, Object).Description copied from interface:LayoutManagerIf the layout manager uses a per-component string, adds the componentcompto the layout, associating it with the string specified byname.- Specified by:
addLayoutComponentin interfaceLayoutManager- Parameters:
name- the string to be associated with the componentcomp- the component to be added
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removeLayoutComponent
Removes the specified component from this border layout. This method is called when a container calls itsremoveorremoveAllmethods. Most applications do not call this method directly.- Specified by:
removeLayoutComponentin interfaceLayoutManager- Parameters:
comp- the component to be removed.- See Also:
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getLayoutComponent
Gets the component that was added using the given constraint- Parameters:
constraints- the desired constraint, one ofCENTER,NORTH,SOUTH,WEST,EAST,PAGE_START,PAGE_END,LINE_START,LINE_END- Returns:
- the component at the given location, or
nullif the location is empty - Throws:
IllegalArgumentException- if the constraint object is not one of the nine specified constants- Since:
- 1.5
- See Also:
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getLayoutComponent
Returns the component that corresponds to the given constraint location based on the targetContainer's component orientation. Components added with the relative constraintsPAGE_START,PAGE_END,LINE_START, andLINE_ENDtake precedence over components added with the explicit constraintsNORTH,SOUTH,WEST, andEAST. TheContainer's component orientation is used to determine the location of components added withLINE_STARTandLINE_END.- Parameters:
target- theContainerused to obtain the constraint location based on the targetContainer's component orientation.constraints- the desired absolute position, one ofCENTER,NORTH,SOUTH,EAST,WEST- Returns:
- the component at the given location, or
nullif the location is empty - Throws:
IllegalArgumentException- if the constraint object is not one of the five specified constantsNullPointerException- if the target parameter is null- Since:
- 1.5
- See Also:
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getConstraints
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minimumLayoutSize
Determines the minimum size of thetargetcontainer using this layout manager.This method is called when a container calls its
getMinimumSizemethod. Most applications do not call this method directly.- Specified by:
minimumLayoutSizein interfaceLayoutManager- Parameters:
target- the container in which to do the layout.- Returns:
- the minimum dimensions needed to lay out the subcomponents of the specified container.
- See Also:
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preferredLayoutSize
Determines the preferred size of thetargetcontainer 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
getPreferredSizemethod.- Specified by:
preferredLayoutSizein interfaceLayoutManager- Parameters:
target- the container in which to do the layout.- Returns:
- the preferred dimensions to lay out the subcomponents of the specified container.
- See Also:
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maximumLayoutSize
Returns the maximum dimensions for this layout given the components in the specified target container.- Specified by:
maximumLayoutSizein interfaceLayoutManager2- Parameters:
target- the component which needs to be laid out- Returns:
- the maximum size of the container
- See Also:
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getLayoutAlignmentX
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:
getLayoutAlignmentXin interfaceLayoutManager2- Parameters:
parent- the target container- Returns:
- the x-axis alignment preference
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getLayoutAlignmentY
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:
getLayoutAlignmentYin interfaceLayoutManager2- Parameters:
parent- the target container- Returns:
- the y-axis alignment preference
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invalidateLayout
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.- Specified by:
invalidateLayoutin interfaceLayoutManager2- Parameters:
target- the target container
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layoutContainer
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
BorderLayoutobject. TheNORTHandSOUTHcomponents, if any, are placed at the top and bottom of the container, respectively. TheWESTandEASTcomponents are then placed on the left and right, respectively. Finally, theCENTERobject 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
doLayoutmethod.- Specified by:
layoutContainerin interfaceLayoutManager- Parameters:
target- the container in which to do the layout.- See Also:
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toString
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addLayoutComponent(Component, Object).