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Class java.awt.Container

java.lang.Object
    |
    +----java.awt.Component
            |
            +----java.awt.Container
Subclasses:
Box, CellRendererPane, JComponent, Panel, ScrollPane, Window

public 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).

Since:
JDK1.0
See Also:
add(java.awt.Component, int), getComponent(int), LayoutManager

Fields inherited from class java.awt.Component
 BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
 

Constructor Summary
 Container()
Constructs a new Container.
 

Method Summary
Component  add(Component comp)
Adds the specified component to the end of this container.
Component  add(String name, Component comp)
Adds the specified component to this container.
Component  add(Component comp, int index)
Adds the specified component to this container at the given position.
void  add(Component comp, Object constraints)
Adds the specified component to the end of this container.
void  add(Component comp, Object constraints, int index)
Adds the specified component to this container with the specified constraints at the specified index.
void  addContainerListener(ContainerListener l)
Adds the specified container listener to receive container events from this container.
void  addImpl(Component comp, Object constraints, int index)
Adds the specified component to this container at the specified index.
void  addNotify()
Notifies the container to create a peer.
int  countComponents()
  Deprecated
void  deliverEvent(Event e)
  Deprecated
void  doLayout()
Causes this container to lay out its components.
Component  findComponentAt(int x, int y)
Locates the visible child component that contains the specified position.
Component  findComponentAt(Point p)
Locates the visible child component that contains the specified point.
float  getAlignmentX()
Returns the alignment along the x axis.
float  getAlignmentY()
Returns the alignment along the y axis.
Component  getComponent(int n)
Gets the nth component in this container.
Component  getComponentAt(int x, int y)
Locates the component that contains the x,y position.
Component  getComponentAt(Point p)
Gets the component that contains the specified point.
int  getComponentCount()
Gets the number of components in this panel.
Component[]  getComponents()
Gets all the components in this container.
Insets  getInsets()
Determines the insets of this container, which indicate the size of the container's border.
LayoutManager  getLayout()
Gets the layout manager for this container.
Dimension  getMaximumSize()
Returns the maximum size of this container.
Dimension  getMinimumSize()
Returns the minimum size of this container.
Dimension  getPreferredSize()
Returns the preferred size of this container.
Insets  insets()
  Deprecated
void  invalidate()
Invalidates the container.
boolean  isAncestorOf(Component c)
Checks if the component is contained in the component hierarchy of this container.
void  layout()
  Deprecated
void  list(PrintStream out, int indent)
Prints a listing of this container to the specified output stream.
void  list(PrintWriter out, int indent)
Prints out a list, starting at the specified indention, to the specified print writer.
Component  locate(int x, int y)
  Deprecated
Dimension  minimumSize()
  Deprecated
void  paint(Graphics g)
Paints the container.
void  paintComponents(Graphics g)
Paints each of the components in this container.
String  paramString()
Returns the parameter string representing the state of this container.
Dimension  preferredSize()
  Deprecated
void  print(Graphics g)
Prints the container.
void  printComponents(Graphics g)
Prints each of the components in this container.
void  processContainerEvent(ContainerEvent e)
Processes container events occurring on this container by dispatching them to any registered ContainerListener objects.
void  processEvent(AWTEvent e)
Processes events on this container.
void  remove(int index)
Removes the component, specified by index, from this container.
void  remove(Component comp)
Removes the specified component from this container.
void  removeAll()
Removes all the components from this container.
void  removeContainerListener(ContainerListener l)
Removes the specified container listener so it no longer receives container events from this container.
void  removeNotify()
Notifies this container and all of its subcomponents to remove their peers.
void  setLayout(LayoutManager mgr)
Sets the layout manager for this container.
void  update(Graphics g)
Updates the container.
void  validate()
Validates this container and all of its subcomponents.
void  validateTree()
Recursively descends the container tree and recomputes the layout for any subtrees marked as needing it (those marked as invalid).
 
Methods inherited from class java.awt.Component
 action, add, addComponentListener, addFocusListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addNotify, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getColorModel, getComponentAt, getComponentAt, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getName, getParent, getPeer, getPreferredSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, isEnabled, isFocusTraversable, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, paramString, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate
 
Methods inherited from class java.lang.Object
 clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Container

public 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).
Method Detail

getComponentCount

public int getComponentCount()
Gets the number of components in this panel.
Returns:
the number of components in this panel.
See Also:
getComponent

countComponents

public int countComponents()
Note: countComponents() is deprecated.As of JDK version 1.1, replaced by getComponentCount().


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.

getComponents

public Component[] getComponents()
Gets all the components in this container.
Returns:
an array of all the components in this container.

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

insets

public Insets insets()
Note: insets() is deprecated.As of JDK version 1.1, replaced by getInsets().


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.

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.

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

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

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

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(java.awt.Component), add(java.awt.Component, int), add(java.awt.Component, java.lang.Object), LayoutManager

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

remove

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

removeAll

public void removeAll()
Removes all the components from this container.
See Also:
add, remove

getLayout

public LayoutManager getLayout()
Gets the layout manager for this container.
See Also:
doLayout, setLayout

setLayout

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

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

layout

public void layout()
Note: layout() is deprecated.As of JDK version 1.1, replaced by doLayout().

Overrides:
layout in class Component

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

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

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.

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(java.awt.Container), getPreferredSize

preferredSize

public Dimension preferredSize()
Note: preferredSize() is deprecated.As of JDK version 1.1, replaced by getPreferredSize().

Overrides:
preferredSize in class Component

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(java.awt.Container), getMinimumSize

minimumSize

public Dimension minimumSize()
Note: minimumSize() is deprecated.As of JDK version 1.1, replaced by getMinimumSize().

Overrides:
minimumSize in class Component

getMaximumSize

public Dimension getMaximumSize()
Returns the maximum size of this container.
Overrides:
getMaximumSize in class Component
See Also:
getPreferredSize

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

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

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(java.awt.Graphics)

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(java.awt.Graphics)

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(java.awt.Graphics)

paintComponents

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

printComponents

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

addContainerListener

public void addContainerListener(ContainerListener l)
Adds the specified container listener to receive container events from this container.
Parameters:
l - the container listener

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

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

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

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

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

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

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

findComponentAt

public Component findComponentAt(int x,
                                 int y)
Locates the visible child component that contains the specified position. The top-most child component is returned in the case where there is overlap in the components. If the containing child component is a Container, this method will continue searching for the deepest nested child component. Components which are not visible are ignored during the search.

The findComponentAt method is different from getComponentAt in that getComponentAt only searches the Container's immediate children; if the containing component is a Container, findComponentAt will search that child to find a nested component.

Parameters:
x - the x coordinate
y - the yReturns:
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.
See Also:
contains, getComponentAt

findComponentAt

public Component findComponentAt(Point p)
Locates the visible child component that contains the specified point. The top-most child component is returned in the case where there is overlap in the components. If the containing child component is a Container, this method will continue searching for the deepest nested child component. Components which are not visible are ignored during the search.

The findComponentAt method is different from getComponentAt in that getComponentAt only searches the Container's immediate children; if the containing component is a Container, findComponentAt will search that child to find a nested component.

Parameters:
p - the point.
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.
See Also:
contains, getComponentAt

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

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(int), remove(java.awt.Component)

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; false otherwise.

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

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(java.io.PrintStream, int)

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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