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Class java.awt.BorderLayout

java.lang.Object | +----java.awt.BorderLayout
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. When adding a component to a container with a border layout, use one of these five names, for example: Panel p = new Panel(); p.setLayout(new BorderLayout()); p.add(new Button("Okay"), "South"); As a convenience, BorderLayout interprets the absence of a string specification the same as "Center": Panel p2 = new Panel(); p2.setLayout(new BorderLayout()); p2.add(new TextArea()); // Same as p.add(new TextArea(), "Center");

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("North", new Button("North")); add("South", new Button("South")); add("East", new Button("East")); add("West", new Button("West")); add("Center", new Button("Center")); } }

See Also:
java.awt.Container.add

Variable Index

o CENTER
The center layout constraint (middle of container).
o EAST
The east layout constraint (left side of container).
o NORTH
The north layout constraint (top of container).
o SOUTH
The south layout constraint (bottom of container).
o WEST
The west layout constraint (right side of container).

Constructor Index

o BorderLayout()
Constructs a new border layout with no gaps between components.
o BorderLayout(int, int)
Constructs a border layout with the specified gaps between components.

Method Index

o addLayoutComponent(Component, Object)
Adds the specified component to the layout, using the specified constraint object.
o addLayoutComponent(String, Component)
Deprecated.
o getHgap()
Returns the horizontal gap between components.
o getLayoutAlignmentX(Container)
Returns the alignment along the x axis.
o getLayoutAlignmentY(Container)
Returns the alignment along the y axis.
o getVgap()
Returns the vertical gap between components.
o invalidateLayout(Container)
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.
o layoutContainer(Container)
Lays out the container argument using this border layout.
o maximumLayoutSize(Container)
Returns the maximum dimensions for this layout given the components in the specified target container.
o minimumLayoutSize(Container)
Determines the minimum size of the target container using this layout manager.
o preferredLayoutSize(Container)
Determines the preferred size of the target container using this layout manager, based on the components in the container.
o removeLayoutComponent(Component)
Removes the specified component from this border layout.
o setHgap(int)
Sets the horizontal gap between components.
o setVgap(int)
Sets the vertical gap between components.
o toString()
Returns a string representation of the state of this border layout.

Variables

o NORTH public static final String NORTH
The north layout constraint (top of container).

o SOUTH public static final String SOUTH
The south layout constraint (bottom of container).

o EAST public static final String EAST
The east layout constraint (left side of container).

o WEST public static final String WEST
The west layout constraint (right side of container).

o CENTER public static final String CENTER
The center layout constraint (middle of container).

Constructors

o BorderLayout public BorderLayout()
Constructs a new border layout with no gaps between components.

o BorderLayout public BorderLayout(int hgap, int vgap)
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.
vgap - the vertical gap.

Methods

o getHgap public int getHgap()
Returns the horizontal gap between components.

o setHgap public void setHgap(int hgap)
Sets the horizontal gap between components.

Parameters:
hgap - the horizontal gap between components
o getVgap public int getVgap()
Returns the vertical gap between components.

o setVgap public void setVgap(int vgap)
Sets the vertical gap between components.

Parameters:
vgap - the vertical gap between components
o addLayoutComponent public 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 strings: "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.
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 strings.
See Also:
add
o addLayoutComponent public void addLayoutComponent(String name, Component comp)
Note: addLayoutComponent() is deprecated. replaced by addLayoutComponent(Component, Object).

o removeLayoutComponent public void removeLayoutComponent(Component comp)
Removes the specified component from this border layout. This method is called when a container calls its remove or removeAll methods. Most applications do not call this method directly.

Parameters:
comp - the component to be removed.
See Also:
remove, removeAll
o minimumLayoutSize 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. Most applications do not call this method directly.

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, getMinimumSize
o preferredLayoutSize 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. This method is called when a container calls its getPreferredSize method.

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, getPreferredSize
o maximumLayoutSize public Dimension maximumLayoutSize(Container target)
Returns the maximum dimensions for this layout given the components in the specified target container.

Parameters:
target - the component which needs to be laid out
See Also:
Container, minimumLayoutSize, preferredLayoutSize
o 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.

o 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.

o invalidateLayout public void invalidateLayout(Container target)
Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.

o layoutContainer 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. The North and Southcomponents, 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:
Container, doLayout
o toString public String toString()
Returns a string representation of the state of this border layout.

Returns:
a string representation of this border layout.
Overrides:
toString in class Object
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