javax.swing
class SwingUtilities

java.lang.Object javax.swing.SwingUtilities

All Implemented Interfaces:

SwingConstants

public class SwingUtilities
extends Object
implements SwingConstants

A collection of utility methods for Swing.

calculateInnerArea

public static Rectangle calculateInnerArea(JComponent c,
                                           Rectangle r)

Stores the position and size of the inner painting area of the specified component in r and returns r. The position and size specify the bounds of the component, adjusted so as not to include the border area (the insets). This method is useful for classes that implement painting code.

Parameters:

c - the JComponent in question; if {@code null}, this method returns {@code null}

r - the Rectangle instance to be modified; may be {@code null}

Returns:

{@code null} if the Component is {@code null}; otherwise, returns the passed-in rectangle (if non-{@code null}) or a new rectangle specifying position and size information

computeDifference

public static Rectangle[] computeDifference(Rectangle rectA,
                                            Rectangle rectB)

Convenience returning an array of rect representing the regions within rectA that do not overlap with rectB. If the two Rects do not overlap, returns an empty array

Parameters:

rectA

rectB

computeIntersection

public static Rectangle computeIntersection(int x,
                                            int y,
                                            int width,
                                            int height,
                                            Rectangle dest)

Convenience to calculate the intersection of two rectangles without allocating a new rectangle. If the two rectangles don't intersect, then the returned rectangle begins at (0,0) and has zero width and height.

Parameters:

x - the X coordinate of the first rectangle's top-left point

y - the Y coordinate of the first rectangle's top-left point

width - the width of the first rectangle

height - the height of the first rectangle

dest - the second rectangle

Returns:

dest, modified to specify the intersection

computeStringWidth

public static int computeStringWidth(FontMetrics fm,
                                     String str)

Compute the width of the string using a font with the specified "metrics" (sizes).

Parameters:

fm - a FontMetrics object to compute with

str - the String to compute

Returns:

an int containing the string width

computeUnion

public static Rectangle computeUnion(int x,
                                     int y,
                                     int width,
                                     int height,
                                     Rectangle dest)

Convenience method that calculates the union of two rectangles without allocating a new rectangle.

Parameters:

x - the x-coordinate of the first rectangle

y - the y-coordinate of the first rectangle

width - the width of the first rectangle

height - the height of the first rectangle

dest - the coordinates of the second rectangle; the union of the two rectangles is returned in this rectangle

Returns:

the dest Rectangle

convertMouseEvent

public static MouseEvent convertMouseEvent(Component source,
                                           MouseEvent sourceEvent,
                                           Component destination)

Returns a MouseEvent similar to sourceEvent except that its x and y members have been converted to destination's coordinate system. If source is {@code null}, sourceEvent x and y members are assumed to be into destination's root component coordinate system. If destination is null, the returned MouseEvent will be in source's coordinate system. sourceEvent will not be changed. A new event is returned. the source field of the returned event will be set to destination if destination is non-{@code null} use the translateMouseEvent() method to translate a mouse event from one component to another without changing the source.

Parameters:

source

sourceEvent

destination

convertPoint

public static Point convertPoint(Component source,
                                 int x,
                                 int y,
                                 Component destination)

Convert the point (x,y) in source coordinate system to destination coordinate system. If source is {@code null}, (x,y) is assumed to be in destination's root component coordinate system. If destination is {@code null}, (x,y) will be converted to source's root component coordinate system. If both source and destination are {@code null}, return (x,y) without any conversion.

Parameters:

source

x

y

destination

convertPoint

public static Point convertPoint(Component source,
                                 Point aPoint,
                                 Component destination)

Convert a aPoint in source coordinate system to destination coordinate system. If source is {@code null}, aPoint is assumed to be in destination's root component coordinate system. If destination is {@code null}, aPoint will be converted to source's root component coordinate system. If both source and destination are {@code null}, return aPoint without any conversion.

Parameters:

source

aPoint

destination

convertPointFromScreen

public static void convertPointFromScreen(Point p,
                                          Component c)

Convert a point from a screen coordinates to a component's coordinate system

Parameters:

p - a Point object (converted to the new coordinate system)

c - a Component object

convertPointToScreen

public static void convertPointToScreen(Point p,
                                        Component c)

Convert a point from a component's coordinate system to screen coordinates.

Parameters:

p - a Point object (converted to the new coordinate system)

c - a Component object

convertRectangle

public static Rectangle convertRectangle(Component source,
                                         Rectangle aRectangle,
                                         Component destination)

Convert the rectangle aRectangle in source coordinate system to destination coordinate system. If source is {@code null}, aRectangle is assumed to be in destination's root component coordinate system. If destination is {@code null}, aRectangle will be converted to source's root component coordinate system. If both source and destination are {@code null}, return aRectangle without any conversion.

Parameters:

source

aRectangle

destination

findFocusOwner

public static Component findFocusOwner(Component c)

Return the child Component of the specified Component that is the focus owner, if any.

Parameters:

c - the root of the Component hierarchy to search for the focus owner

Returns:

the focus owner, or null if there is no focus owner, or if the focus owner is not comp, or a descendant of comp

getAccessibleAt

public static Accessible getAccessibleAt(Component c,
                                         Point p)

Returns the Accessible child contained at the local coordinate Point, if one exists. Otherwise returns null.

Parameters:

c

p

Returns:

the Accessible at the specified location, if it exists; otherwise null

getAccessibleChild

public static Accessible getAccessibleChild(Component c,
                                            int i)

Return the nth Accessible child of the object.

Note: as of the Java 2 platform v1.3, it is recommended that developers call Component.AccessibleAWTComponent.getAccessibleIndexInParent() instead of using this method.

Parameters:

c

i - zero-based index of child

Returns:

the nth Accessible child of the object

getAccessibleChildrenCount

public static int getAccessibleChildrenCount(Component c)

Returns the number of accessible children in the object. If all of the children of this object implement Accessible, than this method should return the number of children of this object.

Note: as of the Java 2 platform v1.3, it is recommended that developers call Component.AccessibleAWTComponent.getAccessibleIndexInParent() instead of using this method.

Parameters:

c

Returns:

the number of accessible children in the object.

getAccessibleIndexInParent

public static int getAccessibleIndexInParent(Component c)

Get the index of this object in its accessible parent.

Note: as of the Java 2 platform v1.3, it is recommended that developers call Component.AccessibleAWTComponent.getAccessibleIndexInParent() instead of using this method.

Parameters:

c

Returns:

-1 of this object does not have an accessible parent. Otherwise, the index of the child in its accessible parent.

getAccessibleStateSet

public static AccessibleStateSet getAccessibleStateSet(Component c)

Get the state of this object.

Note: as of the Java 2 platform v1.3, it is recommended that developers call Component.AccessibleAWTComponent.getAccessibleIndexInParent() instead of using this method.

Parameters:

c

Returns:

an instance of AccessibleStateSet containing the current state set of the object

getAncestorNamed

public static Container getAncestorNamed(String name,
                                         Component comp)

Convenience method for searching above comp in the component hierarchy and returns the first object of name it finds. Can return {@code null}, if name cannot be found.

Parameters:

name

comp

getAncestorOfClass

public static Container getAncestorOfClass(Class c,
                                           Component comp)

Convenience method for searching above comp in the component hierarchy and returns the first object of class c it finds. Can return {@code null}, if a class c cannot be found.

Parameters:

c

comp

getDeepestComponentAt

public static Component getDeepestComponentAt(Component parent,
                                              int x,
                                              int y)

Returns the deepest visible descendent Component of parent that contains the location x, y. If parent does not contain the specified location, then null is returned. If parent is not a container, or none of parent's visible descendents contain the specified location, parent is returned.

Parameters:

parent - the root component to begin the search

x - the x target location

y - the y target location

getLocalBounds

public static Rectangle getLocalBounds(Component aComponent)

Return the rectangle (0,0,bounds.width,bounds.height) for the component aComponent

Parameters:

aComponent

getRoot

public static Component getRoot(Component c)

Returns the root component for the current component tree.

Parameters:

c

Returns:

the first ancestor of c that's a Window or the last Applet ancestor

getRootPane

public static JRootPane getRootPane(Component c)

If c is a JRootPane descendant return its JRootPane ancestor. If c is a RootPaneContainer then return its JRootPane.

Parameters:

c

Returns:

the JRootPane for Component c or {@code null}.

getUIActionMap

public static ActionMap getUIActionMap(JComponent component)

Returns the ActionMap provided by the UI in component component.

This will return {@code null} if the UI has not installed an ActionMap.

Parameters:

component

getUIInputMap

public static InputMap getUIInputMap(JComponent component,
                                     int condition)

Returns the InputMap provided by the UI for condition condition in component component.

This will return {@code null} if the UI has not installed a InputMap of the specified type.

Parameters:

component

condition

getWindowAncestor

public static Window getWindowAncestor(Component c)

Returns the first Window ancestor of c, or {@code null} if c is not contained inside a Window.

Parameters:

c - Component to get Window ancestor of.

Returns:

the first Window ancestor of c, or {@code null} if c is not contained inside a Window.

invokeAndWait

public static void invokeAndWait(Runnable doRun)
                          throws InterruptedException,
                                 InvocationTargetException

Causes doRun.run() to be executed synchronously on the AWT event dispatching thread. This call blocks until all pending AWT events have been processed and (then) doRun.run() returns. This method should be used when an application thread needs to update the GUI. It should'nt be called from the EventDispatchThread. Here's an example that creates a new application thread that uses invokeAndWait to print a string from the event dispatching thread and then, when that's finished, print a string from the application thread.

 final Runnable doHelloWorld = new Runnable() {
     public void run() {
         System.out.println("Hello World on " + Thread.currentThread());
     }
 };

 Thread appThread = new Thread() {
     public void run() {
         try {
             SwingUtilities.invokeAndWait(doHelloWorld);
         }
         catch (Exception e) {
             e.printStackTrace();
         }
         System.out.println("Finished on " + Thread.currentThread());
     }
 };
 appThread.start();
 

Note that if the Runnable.run method throws an uncaught exception (on the event dispatching thread) it's caught and rethrown, as an InvocationTargetException, on the caller's thread.

Additional documentation and examples for this method can be found in How to Use Threads, in The Java Tutorial.

As of 1.3 this method is just a cover for java.awt.EventQueue.invokeAndWait().

Parameters:

doRun

Throws:

InterruptedException - if we're interrupted while waiting for the event dispatching thread to finish excecuting doRun.run()

InvocationTargetException - if an exception is thrown while running doRun

invokeLater

public static void invokeLater(Runnable doRun)

Causes doRun.run() to be executed asynchronously on the AWT event dispatching thread. This will happen after all pending AWT events have been processed. This method should be used when an application thread needs to update the GUI. In the following example the invokeLater call queues the Runnable object doHelloWorld on the event dispatching thread and then prints a message.

 Runnable doHelloWorld = new Runnable() {
     public void run() {
         System.out.println("Hello World on " + Thread.currentThread());
     }
 };

 SwingUtilities.invokeLater(doHelloWorld);
 System.out.println("This might well be displayed before the other message.");
 

If invokeLater is called from the event dispatching thread -- for example, from a JButton's ActionListener -- the doRun.run() will still be deferred until all pending events have been processed. Note that if the doRun.run() throws an uncaught exception the event dispatching thread will unwind (not the current thread).

Additional documentation and examples for this method can be found in How to Use Threads, in The Java Tutorial.

As of 1.3 this method is just a cover for java.awt.EventQueue.invokeLater().

Unlike the rest of Swing, this method can be invoked from any thread.

Parameters:

doRun

isDescendingFrom

public static boolean isDescendingFrom(Component a,
                                       Component b)

Return true if a component a descends from a component b

Parameters:

a

b

isEventDispatchThread

public static boolean isEventDispatchThread()

Returns true if the current thread is an AWT event dispatching thread.

As of 1.3 this method is just a cover for java.awt.EventQueue.isDispatchThread().

Returns:

true if the current thread is an AWT event dispatching thread

isLeftMouseButton

public static boolean isLeftMouseButton(MouseEvent anEvent)

Returns true if the mouse event specifies the left mouse button.

Parameters:

anEvent - a MouseEvent object

Returns:

true if the left mouse button was active

isMiddleMouseButton

public static boolean isMiddleMouseButton(MouseEvent anEvent)

Returns true if the mouse event specifies the middle mouse button.

Parameters:

anEvent - a MouseEvent object

Returns:

true if the middle mouse button was active

isRectangleContainingRectangle

public static final boolean isRectangleContainingRectangle(Rectangle a,
                                                           Rectangle b)

Return true if a contains b

Parameters:

a

b

isRightMouseButton

public static boolean isRightMouseButton(MouseEvent anEvent)

Returns true if the mouse event specifies the right mouse button.

Parameters:

anEvent - a MouseEvent object

Returns:

true if the right mouse button was active

layoutCompoundLabel

public static String layoutCompoundLabel(FontMetrics fm,
                                         String text,
                                         Icon icon,
                                         int verticalAlignment,
                                         int horizontalAlignment,
                                         int verticalTextPosition,
                                         int horizontalTextPosition,
                                         Rectangle viewR,
                                         Rectangle iconR,
                                         Rectangle textR,
                                         int textIconGap)

Compute and return the location of the icons origin, the location of origin of the text baseline, and a possibly clipped version of the compound labels string. Locations are computed relative to the viewR rectangle. This layoutCompoundLabel() does not know how to handle LEADING/TRAILING values in horizontalTextPosition (they will default to RIGHT) and in horizontalAlignment (they will default to CENTER). Use the other version of layoutCompoundLabel() instead.

Parameters:

fm

text

icon

verticalAlignment

horizontalAlignment

verticalTextPosition

horizontalTextPosition

viewR

iconR

textR

textIconGap

layoutCompoundLabel

public static String layoutCompoundLabel(JComponent c,
                                         FontMetrics fm,
                                         String text,
                                         Icon icon,
                                         int verticalAlignment,
                                         int horizontalAlignment,
                                         int verticalTextPosition,
                                         int horizontalTextPosition,
                                         Rectangle viewR,
                                         Rectangle iconR,
                                         Rectangle textR,
                                         int textIconGap)

Compute and return the location of the icons origin, the location of origin of the text baseline, and a possibly clipped version of the compound labels string. Locations are computed relative to the viewR rectangle. The JComponents orientation (LEADING/TRAILING) will also be taken into account and translated into LEFT/RIGHT values accordingly.

Parameters:

c

fm

text

icon

verticalAlignment

horizontalAlignment

verticalTextPosition

horizontalTextPosition

viewR

iconR

textR

textIconGap

notifyAction

public static boolean notifyAction(Action action,
                                   KeyStroke ks,
                                   KeyEvent event,
                                   Object sender,
                                   int modifiers)

Invokes actionPerformed on action if action is enabled (and non-{@code null}). The command for the ActionEvent is determined by:

1. If the action was registered via registerKeyboardAction, then the command string passed in ({@code null} will be used if {@code null} was passed in).
2. Action value with name Action.ACTION_COMMAND_KEY, unless {@code null}.
3. String value of the KeyEvent, unless getKeyChar returns KeyEvent.CHAR_UNDEFINED..

This will return true if action is non-{@code null} and actionPerformed is invoked on it.

Parameters:

action

ks

event

sender

modifiers

paintComponent

public static void paintComponent(Graphics g,
                                  Component c,
                                  Container p,
                                  int x,
                                  int y,
                                  int w,
                                  int h)

Paints a component to the specified Graphics. This method is primarily useful to render Components that don't exist as part of the visible containment hierarchy, but are used for rendering. For example, if you are doing your own rendering and want to render some text (or even HTML), you could make use of JLabel's text rendering support and have it paint directly by way of this method, without adding the label to the visible containment hierarchy.

This method makes use of CellRendererPane to handle the actual painting, and is only recommended if you use one component for rendering. If you make use of multiple components to handle the rendering, as JTable does, use CellRendererPane directly. Otherwise, as described below, you could end up with a CellRendererPane per Component.

If c's parent is not a CellRendererPane, a new CellRendererPane is created, c is added to it, and the CellRendererPane is added to p. If c's parent is a CellRendererPane and the CellRendererPanes parent is not p, it is added to p.

The component should either descend from JComponent or be another kind of lightweight component. A lightweight component is one whose "lightweight" property (returned by the Component isLightweight method) is true. If the Component is not lightweight, bad things map happen: crashes, exceptions, painting problems...

Parameters:

g - the Graphics object to draw on

c - the Component to draw

p - the intermediate Container

x - an int specifying the left side of the area draw in, in pixels, measured from the left edge of the graphics context

y - an int specifying the top of the area to draw in, in pixels measured down from the top edge of the graphics context

w - an int specifying the width of the area draw in, in pixels

h - an int specifying the height of the area draw in, in pixels

paintComponent

public static void paintComponent(Graphics g,
                                  Component c,
                                  Container p,
                                  Rectangle r)

Paints a component to the specified Graphics. This is a cover method for {@link #paintComponent(Graphics,Component,Container,int,int,int,int)}. Refer to it for more information.

Parameters:

g - the Graphics object to draw on

c - the Component to draw

p - the intermediate Container

r - the Rectangle to draw in

processKeyBindings

public static boolean processKeyBindings(KeyEvent event)

Process the key bindings for the Component associated with event. This method is only useful if event.getComponent() does not descend from JComponent, or your are not invoking super.processKeyEvent from within your JComponent subclass. JComponent automatically processes bindings from within its processKeyEvent method, hence you rarely need to directly invoke this method.

Parameters:

event - KeyEvent used to identify which bindings to process, as well as which Component has focus.

Returns:

true if a binding has found and processed

replaceUIActionMap

public static void replaceUIActionMap(JComponent component,
                                      ActionMap uiActionMap)

Convenience method to change the UI ActionMap for component to uiActionMap. If uiActionMap is {@code null}, this removes any previously installed UI ActionMap.

Parameters:

component

uiActionMap

replaceUIInputMap

public static void replaceUIInputMap(JComponent component,
                                     int type,
                                     InputMap uiInputMap)

Convenience method to change the UI InputMap for component to uiInputMap. If uiInputMap is {@code null}, this removes any previously installed UI InputMap.

Parameters:

component

type

uiInputMap

updateComponentTreeUI

public static void updateComponentTreeUI(Component c)

A simple minded look and feel change: ask each node in the tree to updateUI() -- that is, to initialize its UI property with the current look and feel.

Parameters:

c

windowForComponent

public static Window windowForComponent(Component c)

Returns the first Window ancestor of c, or {@code null} if c is not contained inside a Window.

Note: This method provides the same functionality as getWindowAncestor.

Parameters:

c - Component to get Window ancestor of.

Returns:

the first Window ancestor of c, or {@code null} if c is not contained inside a Window.