java.awt.BorderLayout Maven / Gradle / Ivy
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package java.awt;
import java.util.Hashtable;
/**
* 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:
*
* Note: The following code examples include classes that do
* not appear in this specification. Their inclusion is purely to
* serve as a demonstration.
*
*
* 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);
*
* 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 1.53, 01/23/03
* @author Arthur van Hoff
* @see java.awt.Container#add(String, Component)
* @since JDK1.0
*/
public class BorderLayout implements LayoutManager2, java.io.Serializable
{
/**
* The north layout constraint (top of container).
*/
public static final String NORTH = "North";
/**
* The south layout constraint (bottom of container).
*/
public static final String SOUTH = "South";
/**
* The east layout constraint (right side of container).
*/
public static final String EAST = "East";
/**
* The west layout constraint (left side of container).
*/
public static final String WEST = "West";
/**
* The center layout constraint (middle of container).
*/
public static final String CENTER = "Center";
// /**
// * Synonym for PAGE_START. Exists for compatibility with previous
// * versions. PAGE_START is preferred.
// *
// * @see #PAGE_START
// * @since 1.2
// */
// public static final String BEFORE_FIRST_LINE = null;
//
// /**
// * Synonym for PAGE_END. Exists for compatibility with previous
// * versions. PAGE_END is preferred.
// *
// * @see #PAGE_END
// * @since 1.2
// */
// public static final String AFTER_LAST_LINE = null;
//
// /**
// * Synonym for LINE_START. Exists for compatibility with previous
// * versions. LINE_START is preferred.
// *
// * @see #LINE_START
// * @since 1.2
// */
// public static final String BEFORE_LINE_BEGINS = null;
//
// /**
// * Synonym for LINE_END. Exists for compatibility with previous
// * versions. LINE_END is preferred.
// *
// * @see #LINE_END
// * @since 1.2
// */
// public static final String AFTER_LINE_ENDS = null;
//
// /**
// * 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 java.awt.Component#getComponentOrientation
// * @since 1.4
// */
// public static final String PAGE_START = null;
//
// /**
// * 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.
// *
// * @see java.awt.Component#getComponentOrientation
// * @since 1.4
// */
// public static final String PAGE_END = null;
//
// /**
// * 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 java.awt.Component#getComponentOrientation
// * @since 1.4
// */
// public static final String LINE_START = null;
//
// /**
// * 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.
// *
// * @see java.awt.Component#getComponentOrientation
// * @since 1.4
// */
// public static final String LINE_END = null;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -8658291919501921765L;
/**
* Constructs a border layout with the horizontal gaps
* between components.
* The horizontal gap is specified by hgap.
*
* @see #getHgap()
* @see #setHgap(int)
*
* @serial
*/
int hgap;
/**
* Constructs a border layout with the vertical gaps
* between components.
* The vertical gap is specified by vgap.
*
* @see #getVgap()
* @see #setVgap(int)
* @serial
*/
int vgap;
/**
* Constant to specify components location to be the
* north portion of the border layout.
* @serial
* @see #getChild(String, boolean)
* @see #addLayoutComponent
* @see #getLayoutAlignmentX
* @see #getLayoutAlignmentY
* @see #removeLayoutComponent
*/
Component north;
/**
* Constant to specify components location to be the
* west portion of the border layout.
* @serial
* @see #getChild(String, boolean)
* @see #addLayoutComponent
* @see #getLayoutAlignmentX
* @see #getLayoutAlignmentY
* @see #removeLayoutComponent
*/
Component west;
/**
* Constant to specify components location to be the
* east portion of the border layout.
* @serial
* @see #getChild(String, boolean)
* @see #addLayoutComponent
* @see #getLayoutAlignmentX
* @see #getLayoutAlignmentY
* @see #removeLayoutComponent
*/
Component east;
/**
* Constant to specify components location to be the
* south portion of the border layout.
* @serial
* @see #getChild(String, boolean)
* @see #addLayoutComponent
* @see #getLayoutAlignmentX
* @see #getLayoutAlignmentY
* @see #removeLayoutComponent
*/
Component south;
/**
* Constant to specify components location to be the
* center portion of the border layout.
* @serial
* @see #getChild(String, boolean)
* @see #addLayoutComponent
* @see #getLayoutAlignmentX
* @see #getLayoutAlignmentY
* @see #removeLayoutComponent
*/
Component center;
// PBP/PP 6203083
/**
* 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.
* @serial
*/
// Component firstLine;
// PBP/PP 6203083
/**
* A relative positioning constant, that can be used instead of
* north, south, east, west or center.
* Please read Description for firstLine.
* @serial
*/
// Component lastLine;
// PBP/PP 6203083
/**
* A relative positioning constant, that can be used instead of
* north, south, east, west or center.
* Please read Description for firstLine.
* @serial
*/
// Component firstItem;
// PBP/PP 6203083
/**
* A relative positioning constant, that can be used instead of
* north, south, east, west or center.
* Please read Description for firstLine.
* @serial
*/
// Component lastItem;
/**
* Constructs a new border layout with
* no gaps between components.
*/
public BorderLayout() { }
/**
* 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.
* @param hgap the horizontal gap.
* @param vgap the vertical gap.
*/
public BorderLayout(int hgap, int vgap) { }
/**
* Returns the horizontal gap between components.
* @since JDK1.1
*/
public int getHgap() { return 0; }
/**
* Sets the horizontal gap between components.
* @param hgap the horizontal gap between components
* @since JDK1.1
*/
public void setHgap(int hgap) { }
/**
* Returns the vertical gap between components.
* @since JDK1.1
*/
public int getVgap() { return 0; }
/**
* Sets the vertical gap between components.
* @param vgap the vertical gap between components
* @since JDK1.1
*/
public void setVgap(int vgap) { }
/**
* 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.
* @param comp the component to be added.
* @param constraints an object that specifies how and where
* the component is added to the layout.
* @see java.awt.Container#add(java.awt.Component, java.lang.Object)
* @exception IllegalArgumentException if the constraint object is not
* a string, or if it not one of the five specified
* constants.
* @since JDK1.1
*/
public void addLayoutComponent(Component comp, Object constraints) { }
/**
* @deprecated replaced by addLayoutComponent(Component, Object).
*/
public void addLayoutComponent(String name, 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.
* @param comp the component to be removed.
* @see java.awt.Container#remove(java.awt.Component)
* @see java.awt.Container#removeAll()
*/
public void removeLayoutComponent(Component comp) { }
/**
* 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.
* @param target the container in which to do the layout.
* @return the minimum dimensions needed to lay out the subcomponents
* of the specified container.
* @see java.awt.Container
* @see java.awt.BorderLayout#preferredLayoutSize
* @see java.awt.Container#getMinimumSize()
*/
public Dimension minimumLayoutSize(Container target) { return null; }
/**
* 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.
* @param target the container in which to do the layout.
* @return the preferred dimensions to lay out the subcomponents
* of the specified container.
* @see java.awt.Container
* @see java.awt.BorderLayout#minimumLayoutSize
* @see java.awt.Container#getPreferredSize()
*/
public Dimension preferredLayoutSize(Container target) { return null; }
/**
* Returns the maximum dimensions for this layout given the components
* in the specified target container.
* @param target the component which needs to be laid out
* @see Container
* @see #minimumLayoutSize
* @see #preferredLayoutSize
*/
public Dimension maximumLayoutSize(Container target) { return null; }
/**
* 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.
*/
public float getLayoutAlignmentX(Container parent) { return 0; }
/**
* 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.
*/
public float getLayoutAlignmentY(Container parent) { return 0; }
/**
* Invalidates the layout, indicating that if the layout manager
* has cached information it should be discarded.
*/
public void invalidateLayout(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 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.
* @param target the container in which to do the layout.
* @see java.awt.Container
* @see java.awt.Container#doLayout()
*/
public void layoutContainer(Container target) { }
/**
* Returns a string representation of the state of this border layout.
* @return a string representation of this border layout.
*/
public String toString() { return null; }
}