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Class java.awt.Container

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Container

public abstract class Container
extends Component
A generic Abstract Window Toolkit(AWT) container object is a component that can contain other AWT components.

Components added to a container are tracked in a list. The order of the list will define the components' front-to-back stacking order within the container. If no index is specified when adding a component to a container, it will be added to the end of the list (and hence to the bottom of the stacking order).

See Also:
add, getComponent, LayoutManager

Constructor Index

 o Container()
Constructs a new Container.

Method Index

 o add(Component)
Adds the specified component to the end of this container.
 o add(Component, int)
Adds the specified component to this container at the given position.
 o add(Component, Object)
Adds the specified component to the end of this container.
 o add(Component, Object, int)
Adds the specified component to this container with the specified constraints at the specified index.
 o add(String, Component)
Adds the specified component to this container.
 o addContainerListener(ContainerListener)
Adds the specified container listener to receive container events from this container.
 o addImpl(Component, Object, int)
Adds the specified component to this container at the specified index.
 o addNotify()
Notifies the container to create a peer.
 o countComponents()
Deprecated.
 o deliverEvent(Event)
Deprecated.
 o doLayout()
Causes this container to lay out its components.
 o getAlignmentX()
Returns the alignment along the x axis.
 o getAlignmentY()
Returns the alignment along the y axis.
 o getComponent(int)
Gets the nth component in this container.
 o getComponentAt(int, int)
Locates the component that contains the x,y position.
 o getComponentAt(Point)
Gets the component that contains the specified point.
 o getComponentCount()
Gets the number of components in this panel.
 o getComponents()
Gets all the components in this container.
 o getInsets()
Determines the insets of this container, which indicate the size of the container's border.
 o getLayout()
Gets the layout manager for this container.
 o getMaximumSize()
Returns the maximum size of this container.
 o getMinimumSize()
Returns the minimum size of this container.
 o getPreferredSize()
Returns the preferred size of this container.
 o insets()
Deprecated.
 o invalidate()
Invalidates the container.
 o isAncestorOf(Component)
Checks if the component is contained in the component hierarchy of this container.
 o layout()
Deprecated.
 o list(PrintStream, int)
Prints a listing of this container to the specified output stream.
 o list(PrintWriter, int)
Prints out a list, starting at the specified indention, to the specified print writer.
 o locate(int, int)
Deprecated.
 o minimumSize()
Deprecated.
 o paint(Graphics)
Paints the container.
 o paintComponents(Graphics)
Paints each of the components in this container.
 o paramString()
Returns the parameter string representing the state of this container.
 o preferredSize()
Deprecated.
 o print(Graphics)
Prints the container.
 o printComponents(Graphics)
Prints each of the components in this container.
 o processContainerEvent(ContainerEvent)
Processes container events occurring on this container by dispatching them to any registered ContainerListener objects.
 o processEvent(AWTEvent)
Processes events on this container.
 o remove(Component)
Removes the specified component from this container.
 o remove(int)
Removes the component, specified by index, from this container.
 o removeAll()
Removes all the components from this container.
 o removeContainerListener(ContainerListener)
Removes the specified container listener so it no longer receives container events from this container.
 o removeNotify()
Notifies this container and all of its subcomponents to remove their peers.
 o setLayout(LayoutManager)
Sets the layout manager for this container.
 o update(Graphics)
Updates the container.
 o validate()
Validates this container and all of its subcomponents.
 o validateTree()
Recursively descends the container tree and recomputes the layout for any subtrees marked as needing it (those marked as invalid).

Constructors

 o Container
 protected Container()
Constructs a new Container. Containers can be extended directly, but are lightweight in this case and must be contained by a parent somewhere higher up in the component tree that is native. (such as Frame for example).

Methods

 o getComponentCount
 public int getComponentCount()
Gets the number of components in this panel.

Returns:
the number of components in this panel.
See Also:
getComponent
 o countComponents
 public int countComponents()
Note: countComponents() is deprecated. As of JDK version 1.1, replaced by getComponentCount().

 o getComponent
 public Component getComponent(int n)
Gets the nth component in this container.

Parameters:
n - the index of the component to get.
Returns:
the nth component in this container.
Throws: ArrayIndexOutOfBoundsException
if the nth value does not exist.
 o getComponents
 public Component[] getComponents()
Gets all the components in this container.

Returns:
an array of all the components in this container.
 o getInsets
 public Insets getInsets()
Determines the insets of this container, which indicate the size of the container's border.

A Frame object, for example, has a top inset that corresponds to the height of the frame's title bar.

Returns:
the insets of this container.
See Also:
Insets, LayoutManager
 o insets
 public Insets insets()
Note: insets() is deprecated. As of JDK version 1.1, replaced by getInsets().

 o add
 public Component add(Component comp)
Adds the specified component to the end of this container.

Parameters:
comp - the component to be added.
Returns:
the component argument.
 o add
 public Component add(String name,
                      Component comp)
Adds the specified component to this container. It is strongly advised to use the 1.1 method, add(Component, Object), in place of this method.

 o add
 public Component add(Component comp,
                      int index)
Adds the specified component to this container at the given position.

Parameters:
comp - the component to be added.
index - the position at which to insert the component, or -1 to insert the component at the end.
Returns:
the component comp
See Also:
remove
 o add
 public void add(Component comp,
                 Object constraints)
Adds the specified component to the end of this container. Also notifies the layout manager to add the component to this container's layout using the specified constraints object.

Parameters:
comp - the component to be added
constraints - an object expressing layout contraints for this component
See Also:
LayoutManager
 o add
 public void add(Component comp,
                 Object constraints,
                 int index)
Adds the specified component to this container with the specified constraints at the specified index. Also notifies the layout manager to add the component to the this container's layout using the specified constraints object.

Parameters:
comp - the component to be added
constraints - an object expressing layout contraints for this
index - the position in the container's list at which to insert the component. -1 means insert at the end. component
See Also:
remove, LayoutManager
 o addImpl
 protected void addImpl(Component comp,
                        Object constraints,
                        int index)
Adds the specified component to this container at the specified index. This method also notifies the layout manager to add the component to this container's layout using the specified constraints object.

This is the method to override if a program needs to track every add request to a container. An overriding method should usually include a call to the superclass's version of the method:

super.addImpl(comp, constraints, index)

Parameters:
comp - the component to be added.
constraints - an object expressing layout contraints for this component.
index - the position in the container's list at which to insert the component, where -1 means insert at the end.
See Also:
add, add, add, LayoutManager
 o remove
 public void remove(int index)
Removes the component, specified by index, from this container.

Parameters:
index - the index of the component to be removed.
See Also:
add
 o remove
 public void remove(Component comp)
Removes the specified component from this container.

Parameters:
comp - the component to be removed
See Also:
add
 o removeAll
 public void removeAll()
Removes all the components from this container.

See Also:
add, remove
 o getLayout
 public LayoutManager getLayout()
Gets the layout manager for this container.

See Also:
doLayout, setLayout
 o setLayout
 public void setLayout(LayoutManager mgr)
Sets the layout manager for this container.

Parameters:
mgr - the specified layout manager
See Also:
doLayout, getLayout
 o doLayout
 public void doLayout()
Causes this container to lay out its components. Most programs should not call this method directly, but should invoke the validate method instead.

Overrides:
doLayout in class Component
See Also:
layoutContainer, setLayout, validate
 o layout
 public void layout()
Note: layout() is deprecated. As of JDK version 1.1, replaced by doLayout().

Overrides:
layout in class Component
 o invalidate
 public void invalidate()
Invalidates the container. The container and all parents above it are marked as needing to be laid out. This method can be called often, so it needs to execute quickly.

Overrides:
invalidate in class Component
See Also:
validate, layout, LayoutManager
 o validate
 public void validate()
Validates this container and all of its subcomponents.

AWT uses validate to cause a container to lay out its subcomponents again after the components it contains have been added to or modified.

Overrides:
validate in class Component
See Also:
validate, invalidate
 o validateTree
 protected void validateTree()
Recursively descends the container tree and recomputes the layout for any subtrees marked as needing it (those marked as invalid). Synchronization should be provided by the method that calls this one: validate.

 o getPreferredSize
 public Dimension getPreferredSize()
Returns the preferred size of this container.

Returns:
an instance of Dimension that represents the preferred size of this container.
Overrides:
getPreferredSize in class Component
See Also:
getMinimumSize, getLayout, preferredLayoutSize, getPreferredSize
 o preferredSize
 public Dimension preferredSize()
Note: preferredSize() is deprecated. As of JDK version 1.1, replaced by getPreferredSize().

Overrides:
preferredSize in class Component
 o getMinimumSize
 public Dimension getMinimumSize()
Returns the minimum size of this container.

Returns:
an instance of Dimension that represents the minimum size of this container.
Overrides:
getMinimumSize in class Component
See Also:
getPreferredSize, getLayout, minimumLayoutSize, getMinimumSize
 o minimumSize
 public Dimension minimumSize()
Note: minimumSize() is deprecated. As of JDK version 1.1, replaced by getMinimumSize().

Overrides:
minimumSize in class Component
 o getMaximumSize
 public Dimension getMaximumSize()
Returns the maximum size of this container.

Overrides:
getMaximumSize in class Component
See Also:
getPreferredSize
 o getAlignmentX
 public float getAlignmentX()
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.

Overrides:
getAlignmentX in class Component
 o getAlignmentY
 public float getAlignmentY()
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.

Overrides:
getAlignmentY in class Component
 o paint
 public void paint(Graphics g)
Paints the container. This forwards the paint to any lightweight components that are children of this container. If this method is reimplemented, super.paint(g) should be called so that lightweight components are properly rendered. If a child component is entirely clipped by the current clipping setting in g, paint() will not be forwarded to that child.

Parameters:
g - the specified Graphics window
Overrides:
paint in class Component
See Also:
update
 o update
 public void update(Graphics g)
Updates the container. This forwards the update to any lightweight components that are children of this container. If this method is reimplemented, super.update(g) should be called so that lightweight components are properly rendered. If a child component is entirely clipped by the current clipping setting in g, update() will not be forwarded to that child.

Parameters:
g - the specified Graphics window
Overrides:
update in class Component
See Also:
update
 o print
 public void print(Graphics g)
Prints the container. This forwards the print to any lightweight components that are children of this container. If this method is reimplemented, super.print(g) should be called so that lightweight components are properly rendered. If a child component is entirely clipped by the current clipping setting in g, print() will not be forwarded to that child.

Parameters:
g - the specified Graphics window
Overrides:
print in class Component
See Also:
update
 o paintComponents
 public void paintComponents(Graphics g)
Paints each of the components in this container.

Parameters:
g - the graphics context.
See Also:
paint, paintAll
 o printComponents
 public void printComponents(Graphics g)
Prints each of the components in this container.

Parameters:
g - the graphics context.
See Also:
print, printAll
 o addContainerListener
 public synchronized void addContainerListener(ContainerListener l)
Adds the specified container listener to receive container events from this container.

Parameters:
l - the container listener
 o removeContainerListener
 public void removeContainerListener(ContainerListener l)
Removes the specified container listener so it no longer receives container events from this container.

Parameters:
l - the container listener
 o processEvent
 protected void processEvent(AWTEvent e)
Processes events on this container. If the event is a ContainerEvent, it invokes the processContainerEvent method, else it invokes its superclass's processEvent.

Parameters:
e - the event
Overrides:
processEvent in class Component
 o processContainerEvent
 protected void processContainerEvent(ContainerEvent e)
Processes container events occurring on this container by dispatching them to any registered ContainerListener objects. NOTE: This method will not be called unless container events are enabled for this component; this happens when one of the following occurs: a) A ContainerListener object is registered via addContainerListener() b) Container events are enabled via enableEvents()

Parameters:
e - the container event
See Also:
enableEvents
 o deliverEvent
 public void deliverEvent(Event e)
Note: deliverEvent() is deprecated. As of JDK version 1.1, replaced by dispatchEvent(AWTEvent e)

Overrides:
deliverEvent in class Component
 o getComponentAt
 public Component getComponentAt(int x,
                                 int y)
Locates the component that contains the x,y position. The top-most child component is returned in the case where there is overlap in the components. This is determined by finding the component closest to the index 0 that claims to contain the given point via Component.contains().

Parameters:
x - the x coordinate
y - the y coordinate
Returns:
null if the component does not contain the position. If there is no child component at the requested point and the point is within the bounds of the container the container itself is returned; otherwise the top-most child is returned.
Overrides:
getComponentAt in class Component
See Also:
contains
 o locate
 public Component locate(int x,
                         int y)
Note: locate() is deprecated. As of JDK version 1.1, replaced by getComponentAt(int, int).

Overrides:
locate in class Component
 o getComponentAt
 public Component getComponentAt(Point p)
Gets the component that contains the specified point.

Parameters:
p - the point.
Returns:
returns the component that contains the point, or null if the component does not contain the point.
Overrides:
getComponentAt in class Component
See Also:
contains
 o addNotify
 public void addNotify()
Notifies the container to create a peer. It will also notify the components contained in this container. This method should be called by Container.add, and not by user code directly.

Overrides:
addNotify in class Component
See Also:
removeNotify
 o removeNotify
 public void removeNotify()
Notifies this container and all of its subcomponents to remove their peers. This method should be invoked by the container's remove method, and not directly by user code.

Overrides:
removeNotify in class Component
See Also:
remove, remove
 o isAncestorOf
 public boolean isAncestorOf(Component c)
Checks if the component is contained in the component hierarchy of this container.

Parameters:
c - the component
Returns:
true if it is an ancestor; true otherwise.
 o paramString
 protected String paramString()
Returns the parameter string representing the state of this container. This string is useful for debugging.

Returns:
the parameter string of this container.
Overrides:
paramString in class Component
 o list
 public void list(PrintStream out,
                  int indent)
Prints a listing of this container to the specified output stream. The listing starts at the specified indentation.

Parameters:
out - a print stream.
indent - the number of spaces to indent.
Overrides:
list in class Component
See Also:
list
 o list
 public void list(PrintWriter out,
                  int indent)
Prints out a list, starting at the specified indention, to the specified print writer.

Overrides:
list in class Component

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