Container

Name

Description

The Container class serves as a general purpose holder of other Component objects.

Class Definition

public abstract class java.awt.Container extends java.awt.Component {
 // Constructors protected Container(); // Instance Methods public Component add (Component component);
public Component add (Component component, int position);
public void add (Component comp, Object constraints); public void add (Component comp, Object constraints, int position); public Component add (String name, Component component);  public void addContainerListener (ContainerListener l); public void addNotify();
public int countComponents();
public void deliverEvent (Event e); public void doLayout(); public float getAlignmentX(); public float getAlignmentY(); public Component getComponent (int n);
public Component getComponentAt (int x, int y); public Component getComponentAt (Point p); public int getComponentCount(); public Component[] getComponents();
public Insets getInsets(); public LayoutManager getLayout();
public Dimension getMaximumSize(); public Dimension getMinimumSize(); public Dimension getPreferredSize(); public Insets insets();
public void invalidate(); public boolean isAncestorOf (Component c); public void layout();  public void list (PrintStream out, int indentation);
public void list (PrintWriter out, int indentation); public Component locate (int x, int y);  public Dimension minimumSize();  public void paint (Graphics g); public void paintComponents (Graphics g);
public Dimension preferredSize();  public void print (Graphics g); public void printComponents (Graphics g);
public void remove (int index); public void remove (Component component);
public void removeAll();
public void removeContainerListener (ContainerListener l); public void removeNotify();
public void setLayout (LayoutManager manager);
public void validate(); // Protected Instance Methods protected void addImpl (Component comp, Object constraints, int index); protected String paramString(); protected void processContainerEvent (ContainerEvent e); protected void processEvent (AWTEvent e); protected void validateTree();
}

Constructors

Container

protected Container()

• Description
• This constructor creates a "lightweight" container. This constructor allows Container to be subclassed using code written entirely in Java.

Instance Methods

add

public Component add (Component component)

• Parameters
• • component
  • Component to add to container.
• Returns
• Component just added.
• Throws
• IllegalArgumentException if you add component to itself.
• Description
• Adds component as the last component in the container.

public Component add (Component component, int position)

• Parameters
• • component
  • Component to add to container.
  • position
  • Position of component; -1 adds the component as the last in the container.
• Returns
• Component just added.
• Throws
• • ArrayIndexOutOfBoundsException
  • If position invalid.
  • IllegalArgumentException
  • If you add Component to itself.
• Description
• Adds component to container at a certain position.

public void add (Component component, Object constraints)

• Parameters
• • component
  • Component to add to container.
  • constraints
  • An object describing constraints on the component being added.
• Description
• Adds component to container subject to contraints.

public void add (Component component, Object constraints, int index)

• Parameters
• • component
  • Component to add to container.
  • constraints
  • An object describing constraints on the component being added.
  • index
  • The position of the component in the container's list.
• Description
• Adds component to container subject to contraints at position index.

public Component add (String name, Component component)

• Parameters
• • name
  • Name of component being added. This parameter is often significant to the layout manager of the container (e.g "North", "Center").
  • component
  • Component to add to container.
• Returns
• Component just added.
• Throws
• • IllegalArgumentException
  • If you add component to itself.
• Description
• Adds the component to the container with the given name. Replaced by the more general add(Component, Object).

addContainerListener

public void addContainerListener (ContainerListener l)

• Parameters
• • l
  • An object that implements the ContainerListener interface.
• Description
• Add a listener for the container events.

addNotify

public void addNotify()

• Overrides
• Component.addNotify()
• Description
• Creates Container's peer and peers of contained components.

countComponents

public int countComponents()

• Returns
• Number of components within Container.

deliverEvent

public void deliverEvent (Event e)

• Parameters
• • e
  • Event instance to deliver.
• Overrides
• Component.deliverEvent(Event)
• Description
• Tries to locate the component contained in the container that should receive the event.

doLayout

public void doLayout()

• Description
• Lays out the container. This method is a replacement for layout().

getAlignmentX

public float getAlignmentX()

• Returns
• A number between 0 and 1 representing the horizontal alignment of this component.
• Overrides
• Component.getAlignmentX()
• Description
• If the container's layout manager implements LayoutManager2, this method returns the getLayoutAlignmentX() value of the layout manager. Otherwise the getAlignmentX() value of Component is returned.

getAlignmentY

public float getAlignmentY()

• Returns
• A number between 0 and 1 representing the vertical alignment of this component.
• Overrides
• Component.getAlignmentY()
• Description
• If the container's layout manager implements LayoutManager2, this method returns the getLayoutAlignmentY() value of the layout manager. Otherwise the getAlignmentY() value of Component is returned.

getComponent

public synchronized Component getComponent (int position)

• Parameters
• • position
  • Position of component to get.
• Throws
• • ArrayIndexOutOfBoundsException
  • If position is invalid.
• Returns
• Component at designated position within Container.

getComponentAt

public Component getComponentAt (int x, int y)

• Parameters
• • x
  • The x coordinate, in this Container's coordinate system.
  • y
  • The y coordinate, in this Container's coordinate system.
• Returns
• Returns the Component containing the give point.

public Component getComponentAt (Point p)

• Parameters
• • p
  • The point to be tested, in this Container's coordinate system.
• Returns
• Returns the Component containing the give point.

getComponentCount

public int getComponentCount()

• Returns
• Returns the number of components in the container.

getComponents

public Component[] getComponents()

• Returns
• Array of components within the container.

getInsets

public Insets getInsets()

• Returns
• The insets of the container.

getLayout

public LayoutManager getLayout()

• Returns
• LayoutManager of Container.

getMaximumSize

public Dimension getMaximumSize()

• Overrides
• Component.getMaximumSize()
• Returns
• The maximum dimensions of the component.

getMinimumSize

public Dimension getMinimumSize()

• Overrides
• Component.getMinimumSize()
• Returns
• The minimum dimensions of the component.

getPreferredSize

public Dimension getPreferredSize()

• Returns
• The preferred dimensions of the component.

insets

public Insets insets()

• Returns
• Current Insets of Container. Replaced by getInsets().

invalidate

public void invalidate()

• Overrides
• Component.invalidate()
• Description
• Sets the container's valid state to false.

isAncestorOf

public boolean isAncestorOf (Component c)

• Parameters
• • c
  • The component in question.
• Returns
• If c is contained in the container's hierarchy, returns true; otherwise false.

layout

public void layout()

• Overrides
• Component.layout()
• Description
• Replaced by doLayout().

list

public void list (PrintStream out, int indentation)

• Parameters
• • out
  • Output Stream to send results to.
  • indentation
  • Indentation to use when printing.
• Overrides
• Component.list(PrintStream, int)
• Description
• Recursively lists all components in Container.

public void list (PrintWriter out, int indentation)

• Parameters
• • out
  • Output Writer to send results to.
  • indentation
  • Indentation to use when printing.
• Overrides
• Component.list(PrintWriter, int)
• Description
• Recursively lists all components in Container.

locate

public Component locate (int x, int y)

• Parameters
• • x
  • Horizontal position to check.
  • y
  • Vertical position to check.
• Returns
• Component within Container at given coordinates, or Container.
• Overrides
• Component.locate(int, int)
• Description
• Replaced by getComponentAt(int, int).

minimizeSize

public Dimension minimumSize()

• Returns
• Minimum dimensions of contained objects.
• Overrides
• Component.minimumSize()
• Description
• Replaced by getMinimumSize().

paint

public void paint (Graphics g)

• Parameters
• • g
  • Graphics context of container.
• Overrides
• Component.paint()
• Description
• This method tells any lightweight components that are children of this container to paint themselves.

paintComponents

public void paintComponents (Graphics g)

• Parameters
• • g
  • Graphics context of Container.
• Description
• Paints the different components in Container.

preferredSize

public Dimension preferredSize()

• Returns
• Preferred dimensions of contained objects.
• Overrides
• Component.preferredSize()
• Description
• Replaced by getPreferredSize().

print

public void print (Graphics g)

• Parameters
• • g
  • Graphics context of container.
• Overrides
• Component.print()
• Description
• This method tells any lightweight components that are children of this container to print themselves.

printComponents

public void printComponents (Graphics g)

• Parameters
• • g
  • Graphics context of Container.
• Description
• Prints the different components in Container.

remove

public void remove (int index)

• Parameters
• • index
  • Index of the component to remove.
• Description
• Removes the component in position index from Container.

public void remove (Component component)

• Parameters
• • component
  • Component to remove.
• Description
• Removes component from Container.

removeAll

public void removeAll()

• Description
• Removes all components from Container.

removeContainerListener

public void removeContainerListener (ContainerListener l)

• Parameters
• • l
  • One of this Container's ContainerListeners.
• Description
• Remove a container event listener.

removeNotify

public void removeNotify()

• Overrides
• Component.removeNotify()
• Description
• Removes Container's peer and peers of contained components.

setLayout

public void setLayout (LayoutManager manager)

• Parameters
• • manager
  • New LayoutManager for Container.
• Description
• Changes LayoutManager of Container.

validate

public void validate()

• Overrides
• Component.validate()
• Description
• Sets Container's valid state to true and recursively validates its children.

Protected Instance Methods

addImpl

protected void addImpl (Component comp, Object constraints, int index)

• Parameters
• • comp
  • The component to add.
  • constraints
  • Constraints on the component.
  • index
  • Position at which to add this component. Pass -1 to add the component at the end.
• Description
• This method adds a component subject to the given constraints at a specific position in the container's list of components. It is a helper method for the various overrides of add().

paramString

protected String paramString()

• Returns
• String with current settings of Container.
• Overrides
• Component.paramString()
• Description
• Helper method for toString() to generate string of current settings.

processContainerEvent

protected void processContainerEvent (ContainerEvent e)

• Parameters
• • e
  • The event to process.
• Description
• Container events are passed to this method for processing. Normally, this method is called by processEvent().

processEvent

protected void processEvent (AWTEvent e)

• Parameters
• • e
  • The event to process.
• Overrides
• Component.processEvent()
• Description
• Low level AWTEvents are passed to this method for processing.

validateTree

protected void validateTree()

• Description
• Descends recursively into the Container's components and recalculates layout for any subtrees that are marked invalid.

See Also

Component, Dimension, Event, Graphics, Insets, LayoutManager, Panel, PrintStream, String, Window