- java.lang.Object
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- java.awt.BorderLayout
 
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- All Implemented Interfaces:
- LayoutManager,- LayoutManager2,- Serializable
 
 public class BorderLayout extends Object implements LayoutManager2, Serializable 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, andCENTER. 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,BorderLayoutinterprets the absence of a string specification the same as the constantCENTER:Panel p2 = new Panel(); p2.setLayout(new BorderLayout()); p2.add(new TextArea()); // Same as p.add(new TextArea(), BorderLayout.CENTER);In addition, BorderLayoutsupports the relative positioning constants,PAGE_START,PAGE_END,LINE_START, andLINE_END. In a container whoseComponentOrientationis set toComponentOrientation.LEFT_TO_RIGHT, these constants map toNORTH,SOUTH,WEST, andEAST, respectively.For compatibility with previous releases, BorderLayoutalso includes the relative positioning constantsBEFORE_FIRST_LINE,AFTER_LAST_LINE,BEFORE_LINE_BEGINSandAFTER_LINE_ENDS. These are equivalent toPAGE_START,PAGE_END,LINE_STARTandLINE_ENDrespectively. 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 NORTHandPAGE_STARTconstants in a container whose orientation isLEFT_TO_RIGHT, only thePAGE_STARTwill be laid out.NOTE: Currently, BorderLayoutdoes not support vertical orientations. TheisVerticalsetting on the container'sComponentOrientationis not respected.The components are laid out according to their preferred sizes and the constraints of the container's size. The NORTHandSOUTHcomponents may be stretched horizontally; theEASTandWESTcomponents may be stretched vertically; theCENTERcomponent 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 BorderLayoutlayout 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:
- Container.add(String, Component),- ComponentOrientation, Serialized Form
 
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Field SummaryFields Modifier and Type Field Description static StringAFTER_LAST_LINESynonym for PAGE_END.static StringAFTER_LINE_ENDSSynonym for LINE_END.static StringBEFORE_FIRST_LINESynonym for PAGE_START.static StringBEFORE_LINE_BEGINSSynonym for LINE_START.static StringCENTERThe center layout constraint (middle of container).static StringEASTThe east layout constraint (right side of container).static StringLINE_ENDThe component goes at the end of the line direction for the layout.static StringLINE_STARTThe component goes at the beginning of the line direction for the layout.static StringNORTHThe north layout constraint (top of container).static StringPAGE_ENDThe component comes after the last line of the layout's content.static StringPAGE_STARTThe component comes before the first line of the layout's content.static StringSOUTHThe south layout constraint (bottom of container).static StringWESTThe west layout constraint (left side of container).
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Constructor SummaryConstructors Constructor Description 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.
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Method SummaryAll Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description voidaddLayoutComponent(Component comp, Object constraints)Adds the specified component to the layout, using the specified constraint object.voidaddLayoutComponent(String name, Component comp)Deprecated.replaced byaddLayoutComponent(Component, Object).ObjectgetConstraints(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.ComponentgetLayoutComponent(Container target, Object constraints)Returns the component that corresponds to the given constraint location based on the targetContainer's component orientation.ComponentgetLayoutComponent(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.DimensionmaximumLayoutSize(Container target)Returns the maximum dimensions for this layout given the components in the specified target container.DimensionminimumLayoutSize(Container target)Determines the minimum size of thetargetcontainer using this layout manager.DimensionpreferredLayoutSize(Container target)Determines the preferred size of thetargetcontainer using this layout manager, based on the components in the container.voidremoveLayoutComponent(Component comp)Removes 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.StringtoString()Returns a string representation of the state of this border layout.
 
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Field Detail- 
NORTHpublic static final String NORTH The north layout constraint (top of container).- See Also:
- Constant Field Values
 
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SOUTHpublic static final String SOUTH The south layout constraint (bottom of container).- See Also:
- Constant Field Values
 
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EASTpublic static final String EAST The east layout constraint (right side of container).- See Also:
- Constant Field Values
 
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WESTpublic static final String WEST The west layout constraint (left side of container).- See Also:
- Constant Field Values
 
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CENTERpublic static final String CENTER The center layout constraint (middle of container).- See Also:
- Constant Field Values
 
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BEFORE_FIRST_LINEpublic static final String BEFORE_FIRST_LINE Synonym for PAGE_START. Exists for compatibility with previous versions. PAGE_START is preferred.- Since:
- 1.2
- See Also:
- PAGE_START, Constant Field Values
 
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AFTER_LAST_LINEpublic static final String AFTER_LAST_LINE Synonym for PAGE_END. Exists for compatibility with previous versions. PAGE_END is preferred.- Since:
- 1.2
- See Also:
- PAGE_END, Constant Field Values
 
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BEFORE_LINE_BEGINSpublic static final String BEFORE_LINE_BEGINS Synonym for LINE_START. Exists for compatibility with previous versions. LINE_START is preferred.- Since:
- 1.2
- See Also:
- LINE_START, Constant Field Values
 
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AFTER_LINE_ENDSpublic static final String AFTER_LINE_ENDS Synonym for LINE_END. Exists for compatibility with previous versions. LINE_END is preferred.- Since:
- 1.2
- See Also:
- LINE_END, Constant Field Values
 
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PAGE_STARTpublic static final String 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:
- Component.getComponentOrientation(), Constant Field Values
 
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PAGE_ENDpublic static final String 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:
- Component.getComponentOrientation(), Constant Field Values
 
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LINE_STARTpublic static final String 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:
- Component.getComponentOrientation(), Constant Field Values
 
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LINE_ENDpublic static final String 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:
- Component.getComponentOrientation(), Constant Field Values
 
 
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Constructor Detail- 
BorderLayoutpublic BorderLayout() Constructs a new border layout with no gaps between components.
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BorderLayoutpublic 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 Detail- 
getHgappublic int getHgap() Returns the horizontal gap between components.- Returns:
- the horizontal gap between components
- Since:
- 1.1
 
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setHgappublic void setHgap(int hgap) Sets the horizontal gap between components.- Parameters:
- hgap- the horizontal gap between components
- Since:
- 1.1
 
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getVgappublic int getVgap() Returns the vertical gap between components.- Returns:
- the vertical gap between components
- Since:
- 1.1
 
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setVgappublic void setVgap(int vgap) Sets the vertical gap between components.- Parameters:
- vgap- the vertical gap between components
- Since:
- 1.1
 
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addLayoutComponentpublic void addLayoutComponent(Component comp, Object constraints) 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 interface- LayoutManager2
- 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:
- Container.add(java.awt.Component, java.lang.Object)
 
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addLayoutComponent@Deprecated public void addLayoutComponent(String name, Component comp) 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 interface- LayoutManager
- Parameters:
- name- the string to be associated with the component
- comp- the component to be added
 
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removeLayoutComponentpublic void removeLayoutComponent(Component comp) 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 interface- LayoutManager
- Parameters:
- comp- the component to be removed.
- See Also:
- Container.remove(java.awt.Component),- Container.removeAll()
 
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getLayoutComponentpublic Component getLayoutComponent(Object constraints) 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
- 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:
- addLayoutComponent(java.awt.Component, java.lang.Object)
 
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getLayoutComponentpublic Component getLayoutComponent(Container target, Object constraints) 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:
- constraints- the desired absolute position, one of- CENTER,- NORTH,- SOUTH,- EAST,- WEST
- target- the- Containerused to obtain the constraint location based on the target- Container's component orientation.
- 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 constants
- NullPointerException- if the target parameter is null
- Since:
- 1.5
- See Also:
- addLayoutComponent(java.awt.Component, java.lang.Object)
 
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getConstraintspublic Object getConstraints(Component comp) Gets the constraints for the specified component- Parameters:
- comp- the component to be queried
- Returns:
- the constraint for the specified component, or null if component is null or is not present in this layout
- Since:
- 1.5
- See Also:
- addLayoutComponent(java.awt.Component, java.lang.Object)
 
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minimumLayoutSizepublic Dimension minimumLayoutSize(Container target) 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 interface- LayoutManager
- 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:
- Container,- preferredLayoutSize(java.awt.Container),- Container.getMinimumSize()
 
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preferredLayoutSizepublic Dimension preferredLayoutSize(Container target) 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 interface- LayoutManager
- 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:
- Container,- minimumLayoutSize(java.awt.Container),- Container.getPreferredSize()
 
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maximumLayoutSizepublic Dimension maximumLayoutSize(Container target) Returns the maximum dimensions for this layout given the components in the specified target container.- Specified by:
- maximumLayoutSizein interface- LayoutManager2
- Parameters:
- target- the component which needs to be laid out
- Returns:
- the maximum size of the container
- See Also:
- Container,- minimumLayoutSize(java.awt.Container),- preferredLayoutSize(java.awt.Container)
 
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getLayoutAlignmentXpublic 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:
- getLayoutAlignmentXin interface- LayoutManager2
- Parameters:
- parent- the target container
- Returns:
- the x-axis alignment preference
 
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getLayoutAlignmentYpublic 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:
- getLayoutAlignmentYin interface- LayoutManager2
- Parameters:
- parent- the target container
- Returns:
- the y-axis alignment preference
 
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invalidateLayoutpublic void invalidateLayout(Container target) Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.- Specified by:
- invalidateLayoutin interface- LayoutManager2
- Parameters:
- target- the target container
 
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layoutContainerpublic 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 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 interface- LayoutManager
- Parameters:
- target- the container in which to do the layout.
- See Also:
- Container,- Container.doLayout()
 
 
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