Using Visual J++ -- Chapter 19

- Using Visual J++ -

Chapter 19 Visual J++ Applet and AWT Class Reference

This chapter presents material differently from the chapters that come before it. This chapter fills in many of the missing holes by describing some details of the pre-defined Visual J++ Applet and AWT classes, data members, and methods. The chapter works as a mini-reference guide to the Applet and AWT pre-defined classes. As stated in this book's introduction, you'll use this chapter as a reference guide as you progress through your Visual J++ programming experiences.

Use import for class libraries
The import command gives you access to a tremendous number of pre-defined class libraries.
Look for other class packages
You can obtain additional class packages from other resources such as the Internet.
Master the Applet and AWT packages
The Applet and AWT class packages contain the most important classes you'll use as a newcomer to Visual J++.
Pre-defined classes save programming effort
If you take advantage of the pre-defined class code, you will be able to concentrate on your applet's primary goals and not worry about the tedious programming details such as I/O and graphics.

The Class Packages

Visual J++ provides a rich collection of pre-defined class packages. Throughout this book, you've seen several of the more important packages. As you'll recall, a class package contains several pre-defined classes and a class can contain both pre-defined data constants and methods. Here are the class packages Visual J++ provides:

Java.applet Produces such Web page applet components as the applet window, color, and interface
Java.awt Supplies the Windows-like controls such as buttons and scrollbars as well as graphics-oriented methods
Java.awt.image Provides bitmap graphic image support
Java.io Supplies file and device input and output
Java.lang Includes the string and math methods
Java.net Contains network-related support
Java.util Supplies data structures you can use for data storage, searching, and retrieval

This chapter concentrates only on the first two, Java.applet and Java.awt, because those are the classes covered in the most detail in this book. If you want to use methods or named constants from these class packages, you generally use the import command to import the class package. For example, to use the init() method, you must import the Java.applet class package like this:

import java.applet.*; // Imports all the class data and methods

Instead of importing the entire package, you can import just the specific class. The heading of each of this chapter's tables contains the specific class that contains the methods that the table describes. For example, you will see that the drawString() method appears in the java.awt.Graphics class. Therefore, either of the following import commands let you use the drawString() method in the rest of the program:

import java.awt.*; // Imports the entire class package

import java.awt.Graphics; // Imports only one class from the package

You do not have to import the Java.lang class specifically to use the methods defined there.

Keep your eyes open for additional class packages you can obtain online or from software companies. Check out some of Appendix B's Web sites for potential class locations. These class packages provide additional functionality to the standard class packages described here.

Each of the class methods described in the following tables contain a prototype method. A prototype is a format that describes the method's parameters and return data types. From the prototype (listed before each method's description) you will be able to determine how to format the method for your own programs. Remember that if a prototype does not contain a return data type or any parameters, no return value or parameters appear when you use the method.

This chapter does not contain a complete class package reference. Visual J++ includes many more methods and named constants than those described here. This chapter's class package tables explain the more common pre-defined class data and methods from the Applet and AWT class packages, which are the class packages that interest most newcomers to Visual J++ and Java.

Check Visual J++'s Books Online (Visual J++'s online help reference material) for the complete list of pre-defined class package data and methods. As you read through these class descriptions, you'll run across class methods and named constants that you may want to use in your own applets. Now that you've mastered the basics needed for using Visual J++, you can add these class methods to your applets to increase the power of your applets and Web sites. As you begin to develop more comprehensive applets, you may want to explore the other class packages not detailed here, such as the networking class package.

The java.applet.Applet Class

You use the java.applet.Applet class for all your primary applet creation and standard operation.

Class Method	Prototype and Description
Applet	Applet() Creates a new applet. You will always inherit your applet from this method.
destroy	destroy() Removes the current applet as well as its resources from memory.
getAppletContext	appletContext getAppletContext() Lets the applet retrieve system environment information.
getAppletInfo	String getAppletInfo() Returns the applet's author, version, and other applet information you set up from the new applet wizard.
getAudioClip	AudioClip getAudioClip(URL [, String]) Returns the audio clip (a sound file) at the URL and (optionally) a string value with the audio clip's name.
getCodeBase	URL getCodeBase() Returns the applet's URL.
getDocumentBase	URL getDocumentBase() Returns the URL of the HTML page in which the applet resides.
getParameter	String getParameter(String) Returns the applet's parameter given the applet's String-based name.
getParameterInfo	String[][] getParameterInfo() Returns a string array containing each of the applet's parameters.
init	init() The method a Java-based program automatically executes right after your applet constructs. Java calls init() the first time Java executes the start() method.
isActive	boolean isActive() Returns a boolean value that represents whether or not the applet is active yet (the applet is not active until the start() method).
play	play(URL [, String]) Plays the audio clip at the URL and returns the audio's name if available.
resize	resize([Dimension] [int, int]) Resizes the applet's borders to the special dimension or, if supplied, to the width and height values specified by the two integer parameters respectively.
showStatus	showStatus(String) Displays the String inside the applet's content window.
start	start() The method a Java-based program automatically executes upon initial execution.
stop	stop() The method a Java-based program automatically executes before the applet terminates.

The Abstract java.applet.AppletContext Class

Each of these class methods is abstract; therefore, you must supply overriding methods so that your derived classes are usable and not abstract also. Use the java.applet.AppletContext class to get information about the browser running the current applet.

Class Method	Prototype and Description
getApplet	abstract Applet getApplet(String) Returns the name of the applet.
showDocument	abstract void showDocument(URL) Displays the document located at the URL.
showStatus	abstract void showStatus(String) Displays the String message in the Applet's context window.

The Abstract java.applet.AudioClip Class

Each of these class methods is abstract; therefore, you must supply overriding methods so that your derived classes are usable and not abstract also. You can derive from this class to play audio files.

Class Method	Prototype and Description
loop	abstract void loop() Plays the audio clip continuously.
play	abstract void play() Plays an audio clip.
Stop	abstract void stop() Stops playing the audio clip if the clip is still in progress.

The java.awt.BorderLayout Class

Use the java.awt.BorderLayout class to place container items (the Windows-like controls) in North, South, East, West, and Center screen regions.

Class Method	Prototype and Description
BorderLayout	BorderLayout([int, int]) Constructs a border layout with (optionally) a horizontal and vertical gap in points.
addLayoutComponent	void addLayoutComponent(String, Component) Adds the component (such as a button or text box) to the location (for example, South) specified by the string.
minimumLayoutSize	Dimension minimumLayoutSize(Container) Call to receive the minimum necessary dimensions of the specified container.
removeLayoutComponent	void removeLayoutComponent(Component) Removes the component from the layout.

The java.awt.Button Class

Use the java.awt.Button class to place and manipulate button components.

Class Method	Prototype and Description
Button	Button([String]) Constructs a new button with (optionally) the string's label.
getLabel	String getLabel() Returns the string value of the label's text.
setLabel	void setLabel(String) Sets the button's label to the string.

The java.awt.Canvas Class

Use the java.awt.Canvas class to place and manipulate button components.

Class Method	Prototype and Description
Canvas	Canvas() Constructs a canvas surface for your drawings.
paint	void paint(Graphics) Paints the current canvas with your drawing. Generally, you inherit from this class and add your own paint() method.

The java.awt.CardLayout Class

Use the java.awt.CardLayout class to place and manipulate tabbed property sheet dialog boxes.

Class Method	Prototype and Description
CardLayout	CardLayout([int, int]) Constructs a new card layout (property sheet) with the optional horizontal and vertical point sized gaps on each edge.
addLayoutComponent	void addLayoutComponent(String, Component) Adds the component to the card layout dialog box and names the component with the string value.
first	void first(Container) Activates the first card (the "top" property sheet).
last	void last(Container) Activates the last card (the "bottom" property sheet).
minimumLayoutSize	Dimension minimumLayoutSize(Container) Call to receive the minimum necessary dimensions of the specified container.
next	void next(Container) Activates the next card (the "next" property sheet) within the card layout.
preferredLayoutSize	Dimension preferredLayoutSize(Container) Call to receive the recommended necessary dimensions of the specified container.
previous	void previous(Container) Activates the previous card (the "former" property sheet) within the card layout.
removeLayoutComponent	void removeLayoutComponent(Component) Removes the component from the layout.
show	void show(Container, String) Displays the component indicated by the string in the specified container.

The java.awt.CheckBox Class

Use the java.awt.CheckBox class to place and manipulate boolean check boxes.

Class Method	Prototype and Description
Checkbox	Checkbox(String [, CheckboxGroup, boolean]) Constructs a new check box with the string label inside (optionally) the group specified. If you include a group, also include the check box's checked or unchecked state with true or false.
getCheckboxGroup	CheckboxGroup getCheckboxGroup() Call to receive the check box's group name.
getLabel	String getLabel() Returns the string value of the check box's text.
getState	boolean getState() Returns the boolean value of the check box's checked or unchecked state.
setCheckboxGroup	void setCheckboxGroup(CheckboxGroup) Sets the group for the current check box.
setLabel	void setLabel(String) Sets the check box's label to the string.
setState	void setState(boolean) Sets the check box to checked or unchecked depending on the true or false value inside the boolean parameter.

The java.awt.CheckBoxMenuItem Class

Use the java.awt.CheckBoxMenuItem class to place a check box item on a menu option.

Class Method	Prototype and Description
CheckboxMenuItem	CheckboxMenuItem(String) Constructs a new check box item on the menu with the label indicated by the string. The check box menu item is initially unchecked (turned off).
getState	boolean getState() Call to receive the menu item's check box state.
setState	void setState(boolean) Sets the menu's check box to checked or unchecked depending on the true or false value inside the boolean parameter.

The java.awt.Choice Class

Use the java.awt.Choice class to place a pop-up menu on your applet.

Class Method	Prototype and Description
Choice	Choice() Constructs a new pop-up choice menu.
addItem	void addItem(String) Adds a new item with the string's label to the pop-up choice menu.
countItems	int countItems() Call to receive the number of items on the pop-up choice menu.
getItem	String getItem(int) Call to receive the label of the item indicated by the integer index parameter.
getSelectedIndex	int getSelectedIndex() Call to receive the index of the pop-up menu's selected choice.
getSelectedItem	String getSelectedItem() Call to receive the label of the pop-up menu's selected choice.
select	void select(int) Selects the pop-up menu choice indicated by the integer index.
select	void select(String) Selects the pop-up menu choice indicated by the string label.

The java.awt.Color Class

Use the java.awt.Color class to control the colors you want in your AWT objects. You can use the following named constants to indicate common specific colors:

Color.black
Color.blue
Color.cyan
Color.darkGray
Color.gray
Color.green
Color.lightGray
Color.magenta
Color.orange
Color.pink
Color.red
Color.white
Color.yellow

Use the following methods to construct and work with colors. The colors are called RGB colors due to their combinations of red, green, and blue combinations.

Class Method	Prototype and Description
Color	Color(int, int, int) Constructs a color with the amount of red, green, and blue components indicated by the three integer parameters respectively. The parameters can range from 0 to 255.
Color	Color(float, float, float) Constructs a color with the amount of red, green, and blue components indicated by the three floating-point parameters respectively. The parameters can range from 0.0 to 1.0 indicating the percentage of red, green, and blue color amounts.
Color	Color(int) Constructs a color given the Windows-based RGB integer value.
brighter	Color brighter() Brightens the color.
darker	Color darker () Darkens the color.
equals	boolean equals(Object) Call to determine if the object is the same color as the current color setting.
getBlue	int getBlue() Call to receive the integer portion of the color's blue amount.
getGreen	int getGreen() Call to receive the integer portion of the color's green amount.
getRed	int getRed() Call to receive the integer portion of the color's red amount.
getRGB	int getRGB() Call to receive the integer RGB combination value of the current color.

The java.awt.Component Class

Use the java.awt.Component class to manipulate an AWT component, or object, such as a button or text box, that appears on your applet's container area.

Class Method	Prototype and Description
action	boolean action(Event, Action) Java automatically calls the action() method when the event triggers the specified action. If you want to handle the action, do so and return true; if you return false (or choose not to handle one or more events or actions), the default AWT handler takes over.
deliverEvent	void deliverEvent(Event) Sends the event to the current component or to a subclassed component.
disable	void disable() Disables the component from operation.
enable	void enable() Enables a disabled component.
enable	void enable(boolean) Enables a disabled component if the boolean value is true and disables a component if the boolean value is false.
getBackground	Color getBackground() Call to get the current background color of the current component.
getFont	Font getFont() Call to receive the font used in the component.
getFontMetrics	FontMetrics getFontMetrics(Font) Call to receive font information about the specified font.
getForeground	Color getForeground() Call to receive the component's foreground color.
getGraphics	Graphics getGraphics() Call to receive the component's graphics context if the component appears on the screen and returns null otherwise.
getParent	Container getParent() Call to receive the parent container.
gotFocus	void gotFocus() Your applet automatically calls this method when the component gets the focus (the highlight to receive keyboard input).
handleEvent	boolean handleEvent(Event) Your applet automatically calls this method when the event occurs. When you want to handle a particular event, override this method by returning true; return false if you want the default event handler to intercept the event.
hide	void hide() Turns the component invisible.
inside	boolean inside(int, int) Call to determine if your x- and y-coordinates, indicated by the two integer parameters respectively, fall within the component's area.
invalidate	void invalidate() Invalidates the current component.
isEnabled	boolean isEnabled() Call to find out if the current component is enabled.
isShowing	boolean isShowing() Call to find out if the current component is enabled or disabled.
isValid	void isValid() Call to find out if the current component is valid or invalid.
isVisible	boolean isVisible() Call to find out if the current component is visible or hidden.
keyDown	boolean keyDown(Event, int) Your applet calls this method if the event is triggered by the specific integer keypress.
keyUp	boolean keyUp(Event, int) Your applet calls this method if the event is triggered by the specific integer key release.
layout	void layout() Sets up the layout for this component.
locate	Component locate(int, int) Call to receive the component located at the x- or y-coordinate.
location	Point location() Call to receive the current x- and y-coordinate location of this component.
lostFocus	void lostFocus() Your applet calls this method when the current component loses its focus.
mouseDown	boolean mouseDown(event, int, int) Your applet calls this method when the mouse button is pressed at the coordinate location indicated by the two integer parameters.
mouseDrag	boolean mouseDrag(event, int, int) Your applet calls this method when the mouse is dragged at the coordinate location indicated by the two integer parameters.
mouseEnter	boolean mouseEnter(event, int, int) Your applet calls this method when the mouse is moved into the coordinate location indicated by the two integer parameters.
mouseExit	boolean mouseExit(event, int, int) Your applet calls this method when the mouse is moved out of the coordinate location indicated by the two integer parameters.
mouseMove	boolean mouseMove(event, int, int) Your applet calls this method when the mouse is moved at the coordinate location indicated by the two integer parameters.
mouseUp	boolean mouseUp(event, int, int) Your applet calls this method when the mouse button is released at the coordinate location indicated by the two integer parameters.
move	void move(int, int) Moves the component to the integer x- and y-locations.
nextFocus	void nextFocus() Moves the component focus to the next focus in the container.
paint	void paint(Graphics) Paints the component on the graphics context.
paintAll	void paintAll(Graphics) Paints the component and all child components on the graphics context.
postEvent	void postEvent(Event) Forces the specified event so that the handleEvent() method is called.
prepareImage	boolean prepareImage(Image, [int, int,] ImageObserver) Prepares the image for viewing on the current component and returns a true value when the image is ready. Specify the two integer width and height parameters if you want to use those values for the image.
print	void print(Graphics) Prints the current component in the graphics context.
printAll	void printAll(Graphics) Prints the current component and all child components in the graphics context.
repaint	void repaint(long) Automatically calls the update method as soon as Java can redraw the component or at least before the long integer millisecond value.
resize	void resize(int, int) Changes the size of the current component to the integer x- and y-coordinates.
setBackground	void setBackground(Color) Sets the current component's background color.
setFont	void setFont(Font) Sets the current component's font.
setForeground	void setForeground(Color) Sets the current component's foreground color.
show	void show() Shows the current component.
show	void show(boolean) Shows the current component if the boolean value is true.
size	Dimension size() Call to receive the size of the current component.
update	void update(Graphics) Updates the component (but not the background) when the repaint() method executes.
validate	void validate() Validates the current component.

The java.awt.Container Class

Use the java.awt.Container class to manipulate an AWT container that holds one or more components.

Class Method	Prototype and Description
add	Component add(Component, int) Adds the component to the current container at the integer index position. If the integer index is -1, the component appears at the end of the container.
add	Component add([String,] Component) Adds the component to the current container and adds the container at the optional string specified location (such as "West").
countComponents	int countComponents() Call to receive the number of components in the current container.
deliverEvent	void deliverEvent(Event) Sends the event to the current container's component that can receive the event.
getComponent	Component getComponent(int) Call to receive the component located at the integer index position inside the current container.
getComponents	Component[] getComponent() Call to receive every component into an array.
locate	Component locate(int, int) Call to receive the component located at the integers' x- and y-coordinates.
paintComponents	void paintComponents(Graphics) Paints the components on the graphics context.
remove	void remove(Component) Removes the specified component from the current container.
removeAll	void removeAll() Removes every specified component from the current container.
setLayout	void setLayout(LayoutManager) Sets the current container's layout.
validate	void validate() Validates the current container.

The java.awt.Dialog Class

Use the java.awt.Dialog class to create and manipulate an AWT dialog box.

Class Method	Prototype and Description
Dialog	Dialog(Frame [, String], boolean) Constructs the new dialog box with the optional string for the title. The frame indicates the dialog box's parent and whether or not the parent is modal (true), meaning the dialog box will intercept all input, or not modal (false), if other events can intercept the keystrokes.
getTitle	String getTitle() Call to receive the dialog box's title.
isModal	boolean isModal() Call to determine if the dialog box is modal or not.
isResizable	boolean isResizable() Call to determine if the dialog box is resizable.
setResizable	void setResizable(boolean) Call to let the user set the dialog box's size (if true) or to keep the user from setting the dialog box's size (if false).
setTitle	void setTitle(String) Adds a new string title to the current dialog box.

The java.awt.Event Class

Use the java.awt.Event class to control AWT container events. The most important member elements of this class are the named constants that represent possible events shown here:

Event.ACTION_EVENT The most recent event triggered.
Event:DOWN The user pressed the Down arrow.
Event:END The user pressed the End key.
Event:F1 through Event:F12 The user pressed one of the function keys.
Event:HOME The user pressed the Home key.
Event:LEFT The user pressed the Left key.
Event:PGDN The user pressed the PageDown key.
Event:PGUP The user pressed the PageUp key.
Event:RIGHTcThe user pressed the Right key.
Event:UP The user pressed the Up key.
Event:ALT_MASK The user pressed the Alt key along with, possibly, another key.
Event:CTRL_MASK The user pressed the Ctrl key along with, possibly, another key.
Event:SHIFT_MASK The user pressed the Shift key along with, possibly, another key.
Event:META_MASK Indicates, if a mouse event occurred, that the user clicked the right mouse button.
Event.KEY_ACTION A keyboard event occurred.
Event.KEY_ACTION_RELEASE A keyboard action key was released causing an event.
Event,KEY_PRESS The user pressed a key.
Event.KEY_RELEASE The user released a key.
Event.LIST_DESELECT The user deselected a list's item.
Event.LIST_SELECT The user selected a list's item.
Event.LOAD_FILE A file is loading.
Event:MOUSE_DOWN The mouse button was pressed.
Event:MOUSE_DRAG The mouse was dragged.
Event:MOUSE_ENTER The mouse entered an area.
Event:MOUSE_EXIT The mouse exited an area.
Event:MOUSE_MOVE The mouse was moved.
Event:MOUSE_UP The mouse button was released.
Event:SAVE_FILE A file is being saved.
Event:SCROLL_ABSOLUTE An absolute scroll took place (the user scrolled to a specific area on the scrollbar).
Event:SCROLL_LINE_DOWN A minimum scroll down took place (the user clicked the down scroll arrow).
Event:SCROLL_LINE_UP A minimum scroll up took place (the user clicked the up scroll arrow).
Event:SCROLL_PAGE_DOWN A page scroll down took place (the user clicked within the scroll area between the scrollbar and the scroll down arrow).
Event:SCROLL_PAGE_UP A page scroll up took place (the user clicked within the scroll area between the scrollbar and the scroll up arrow).
Event:WINDOW_DEICONIFY The window was maximized.
Event:WINDOW_DESTROY The window was closed.
Event:WINDOW_EXPOSE The window was exposed.
Event:WINDOW_ICONIFY The window was minimized.
Event:WINDOW_MOVED The window was moved.

Use the following methods to construct and work with events.

Class Method	Prototype and Description
controlDown	boolean controlDown() Call to determine if the user pressed the Ctrl key.
metaDown	boolean metaDown() Call to determine if the user pressed the designated meta key (a key that triggers a command).
shiftDown	boolean shiftDown() Call to determine if the user pressed the Shift key.
translate	void translate(int, int) Determines the event at the location specified by the integer x- and y-coordinates.

The java.awt.FileDialog Class

Use the java.awt.FileDialog class to control Windows-like file selection dialog boxes. You can use the following named constants for testing the two primary file-related events:

FileDialog.LOAD The file load constant
FileDialog.SAVE The file save constant

Use the following methods to construct and work with file-related dialog boxes.

Class Method	Prototype and Description
getDirectory	String getDirectory() Call to receive the selected directory within the file dialog box.
getFile	String getFile() Call to receive the selected file within the file dialog box.
getFilenameFilter	String getFilenameFilter() Call to receive the selected file-name filter (such as .txt or .html within the file dialog box.
getMode	String getMode() Call to receive the load or save state of the file dialog box (use the named constants for testing).
setDirectory	void setDirectory(String) Call to set the file dialog box's directory to the string parameter.
setFile	void setFile(String) Call to set the file dialog box's file to the string parameter.
setFilenameFilter	void setFilenameFilter(FileNameFilter) Call to set the file dialog box's file-name wildcard filter to the specified parameter.

The java.awt.FlowLayout Class

Use the java.awt.FlowLayout class to control the layout of the containers on which you place your AWT components. You can use the following named constants for determining the components' layout flow:

FlowLayout.CENTER Centers the container's components
FlowLayout.LEFT Left-justifies the container's components
FlowLayout.RIGHT Right-justifies the container's components

Use the following methods to construct the flow layouts. A few flow layout container manipulation methods exist, but they are not covered here.

Class Method	Prototype and Description
FlowLayout	FlowLayout([int]) Constructs a flow layout container with the optional alignment specified (use the named constants).
FlowLayout	FlowLayout(int, int, int) Constructs a flow layout container with the integer alignment, integer horizontal gap, and integer vertical point gap (the space between components).

The java.awt.Font Class

Use the java.awt.Font class to define and change the font used with components. The following data members help you control the fonts you use:

Font.BOLD Boldfaces the current font.
Font.ITALIC Italicizes the current font.
Font.name Selects the name of the font style to use.
Font.PLAIN Resets the font's default style.
Font.size Selects the size, in points, of the font style to use.
Font.style Adds the Font.BOLD, Font.ITALIC, and Font.PLAIN styles if you want to combine styles such as a boldfaced italic font (assuming your font system is capable of producing that combination).

Use the following methods to construct and manipulate your fonts.

Class Method	Prototype and Description
Font	Font(String, int, int) Constructs the specified font style from the string name with the specified integer style and integer point sizes.
equals	boolean equals(Object) Use to see if the object's font is equal to the current object's font.
getFamily	String getFamily() Call to receive the current font's family name.
getFont	Font getFont(String [, Font]) Returns the font given the string's property. If getFont() can find no matching font, the system returns the default font that you optionally specify.
getName	String getName() Returns the current font's name.
getSize	String getSize() Returns the current font's size.
getStyle	String getStyle() Returns the current font's style.
isBold	boolean isBold() True if the current font is boldfaced.
isItalic	boolean isItalic() True if the current font is italicized.
isPlain	boolean isPlain() true if the current font is a plain font with no special formatting.

The java.awt.FontMetrics Class

Use the java.awt.FontMetrics class to define and change the font metrics used with components. The font metrics describe a font's size and statistics.

Class Method	Prototype and Description
FontMetrics	FontMetrics(Font) Constructs the specified font metrics-defined component.
charWidth	int charWidth(char) Returns the integer point size of the specified character.
getAscent	int getAscent() Returns the integer point size of the character's height above the font's baseline.
getDescent	int getDescent() Returns the integer point size of the character's height below the font's baseline.
getFont	Font getFont() Call to receive the name of the current font.
getHeight	Font getHeight() Call to receive the height of the current font.
getLeading	Font getLeading() Call to receive the current font's full height.
getMaxAdvance	int getMaxAdvance() Call to receive the maximum advance point width for the font's characters.
getMaxAscent	int getMaxAscent() Call to receive the maximum point size ascent value for the font's largest characters.
getMaxDescent	int getMaxDescent() Call to receive the maximum point size descent value for the font's largest characters.
getWidths	int [] getWidths() Call to receive an integer array of the 256 ASCII characters.
stringWidth	int stringWidth(String) Call to receive the width of the string you specify.

The java.awt.Frame Class

Use the java.awt.Frame class to define and change a window. The window frame is initially invisible and has no title. The following data members help you control the fonts you use:

Frame.CROSSHAIR_CURSOR Specifies the crosshair pinpointing mouse cursor
Frame.DEFAULT_CURSOR Specifies the default pointing mouse cursor
Frame.E_RESIZE_CURSOR Specifies the east-pointing resizing double-arrow mouse cursor
Frame.HAND_CURSOR Specifies the hand-shaped mouse cursor
Frame.MOVE_CURSOR Specifies the moving mouse cursor
Frame.N_RESIZE_CURSOR Specifies the north-pointing resizing double-arrow mouse cursor
Frame.NE_RESIZE_CURSOR Specifies the northeast-pointing resizing double-arrow mouse cursor
Frame.NW_RESIZE_CURSOR Specifies the northwest-pointing resizing double-arrow mouse cursor
Frame.S_RESIZE_CURSOR Specifies the south-pointing resizing double-arrow mouse cursor
Frame.SE_RESIZE_CURSOR Specifies the southeast-pointing resizing double-arrow mouse cursor
Frame.SW_RESIZE_CURSOR Specifies the southwest-pointing resizing double-arrow mouse cursor
Frame.TEXT_CURSOR Specifies the text-insertion mouse cursor
Frame.W_RESIZE_CURSOR Specifies the west-pointing resizing double-arrow mouse cursor
Frame.WAIT_CURSOR Specifies the hourglass waiting mouse cursor

Use the following methods to construct and manipulate frames.

Class Method	Prototype and Description
Frame	Frame([String]) Constructs a new frame with the optional title.
dispose	void dispose() Releases the frame's resources and gets rid of the frame. Call this method when you finish with the frame.
getCursorType	int getCursorType() Call to receive the cursor type that you can test with the pre-defined named cursor constants.
getIconImage	Image getIconImage() Call to receive the frame's icon.
getMenuBar	MenuBar getMenuBar() Call to receive the frame's menu bar.
getTitle	String getTitle() Call to receive the frame's title.
isResizable	boolean isResizable() Informs you if the frame is resizable.
remove	void remove(MenuComponent) Removes the menu from the frame.
setCursor	void setCursor(int) Changes the cursor to the integer cursor definition (use the pre-defined cursor named constants).
setIconImage	void setIconImage(Image) Specifies the frame's icon that appears when the user minimizes the frame.
setmenuBar	void setMenuBar(MenuBar) Specifies which menu bar goes with the current frame.
setResizable	void setResizable(boolean) Specifies whether or not the end-user can resize the frame.
setTitle	void setTitle(String) Specifies the frame's title.

The java.awt.Graphics Class

Use the java.awt.Graphics class to create and manipulate your applet's graphic elements.

Class Method	Prototype and Description
clearRect	abstract void clearRect(int, int, int, int) Fills the rectangle region specified by the integer x-coordinate, y-coordinate, width, and height parameters with the background color, effectively erasing the rectangle.
copyArea	abstract void copyArea(int, int, int, int, int, int) Copies the area specified by the first four integer parameters (the x-coordinate, y-coordinate, width, and height parameters) to the final two integer x- and y-coordinates.
create	abstract Graphics create([int, int, int, int]) Makes a copy of the current graphics object. If you specify the optional x-coordinate, y-coordinate, width, and height parameters, the copy is made based on these parameters.
dispose	abstract void dispose() Eliminates the current graphics object.
draw3DRect	void draw3DRect(int, int, int, int, boolean) Draws a 3D rectangle using the x-coordinate, y-coordinate, width, and height parameters, and raises the rectangle if the boolean parameter is true.
drawArc	abstract void drawArc(int, int, int, int, int, int) Draws an arc whose center falls in the first two integer parameters x- and y-coordinates with the size specified by the third and fourth integer width and height parameters. The arc draws from the start angle indicated by the fifth argument to the final argument (indicated in degrees).
drawChars	void drawChars(char [], int, int, int, int) Draws the characters located in the character array. The second argument indicates the offset of the starting array character to draw and the third parameter indicates the length of the array. The last two parameters indicate the x- and y-coordinates.
drawImage	abstract boolean drawImage(Image, int, int [, int, int], ImageObserver) Draws the image at the x- and y-coordinates indicated by the second and third parameters. The optional parameters determine the width and height if you want to specify those values. The ImageObserver notifies you once the image is completely drawn.
drawImage	abstract boolean drawImage(Image, int, int [, int, int], Color, ImageObserver] Augments the previous drawImage() method by specifying the image's color.
drawLine	abstract void drawLine(int, int, int, int) Draws a line from the first two integer coordinates to the last two integer coordinates.
drawOval	abstract void drawOval(int, int, int, int) Draws an oval inside an imaginary rectangle specified by the four integer coordinates.
drawPolygon	abstract void drawPolygon(int[], int[], int) Draws a multi-sided figure using the multiple coordinates specified by the two integer array parameters for the number of points specified by the final parameter.
drawPolygon	abstract void drawPolygon(Polygon) Draws a polygon based on the polygon parameter's characteristics.
drawRect	void drawRect(int, int, int, int) Draws a rectangle at the first two integer coordinates with the width and height point values specified by the last two parameters.
drawRoundRect	void drawRoundRect(int, int, int, int, int, int) Draws a rounded rectangle at the first two integer coordinates with the width and height point values specified by the last two parameters. The final two parameters indicate the arc's width and height values for the rounded corners.
drawString	abstract void drawString(String, int, int) Draws the indicated string starting at the integer coordinates.
fill3DRect	void fill3DRect(int, int, int, int, boolean) Paints a 3D rectangle using the drawRect() coordinates using the current color.
fillArc	abstract void fillArc(int, int, int, int, int, int) Paints an arc using the drawArc() coordinates using the current color.
fillOval	abstract void fillOval(int, int, int, int) Paints an oval using the drawOval() coordinates using the current color.
fillPolygon	abstract void fillPolygon(int[], int[], int) Paints a polygon using the drawPolygon() coordinates using the current color.
fillRect	abstract void fillRect(int, int, int, int) Paints a rectangle using the drawRect() coordinates using the current color.
fillRoundRect	abstract void fillRoundRect(int, int, int, int, int, int) Paints a rounded rectangle using the drawRoundRect() coordinates using the current color.
finalize	void finalize() Calls the current graphics context dispose() method, which eliminates the graphics context when you are finished with the context.
getColor	abstract Color getColor() Call to receive the current color.
getFont	abstract Font getFont() Call to receive the current font.
getFontMetrics	abstract FontMetrics getFontMetrics() Call to receive the current font's metrics.
getFontMetrics	abstract FontMetrics getFontMetrics(Font) Call to receive the font parameter's font metrics.
setColor	abstract setColor(Color) Sets the current color to the color parameter.
setFont	abstract setFont(Font) Sets the current font to the font parameter.

The java.awt.Image Class

Use the java.awt.Image class to create and manipulate your applet's graphic images.

Class Method	Prototype and Description
flush	abstract void flush() Eliminates all resources used by the current image.
getGraphics	abstract Graphics getGraphics() Call to receive a graphics object to draw into the current offscreen image.
getheight	abstract int getHeight(ImageObserver) Call to receive th height, in pixels, of the current image. If the image is not yet defined, getHeight() returns -1 and the ImageObserver is notified at the completion of the image.
getSource	Abstract ImageProducer getSource() Call to receive the image producer for the current image's pixels.
getWidth	abstract int getWidth(ImageObserver) Call to receive the width, in pixels, of the current image. If the image is not yet defined, getWidth() returns -1 and the ImageObserver is notified at the completion of the image.

The java.awt.Label Class

Use the java.awt.Label class to create and manipulate your applet's labels. Use the following alignment named constants for aligning your label captions:

Label.CENTER Centers a caption on a label
Label.LEFT Left-justifies a caption on a label
Label.RIGHT Right-justifies a caption on a label

Use the following methods to create and manipulate labels.

Class Method	Prototype and Description
Label	Label() Constructs a new and empty label.
Label	Label(String [, int]) Constructs a new label with the string caption and optional alignment value.
getAlignment	int getAlignment() Call to receive the current label's alignment.
getText	String getText() Call to receive the current label's caption.
setAlignment	void setAlignment(int) Call to specify the current label's alignment. Use the named alignment constants.
setText	void setText(String) Call to specify the current label's caption.

The java.awt.Label Class

Use the java.awt.Label class to create and manipulate your applet's labels. Use the following methods to create and manipulate labels.

Class Method	Prototype and Description
List	List([int, boolean]) Constructs a scrolling list with the optional integer parameter's rows and allows for multiple selections (using Ctrl+Click) if you specify the optional boolean true parameter.
addItem	void addItem(String, int) Adds the string item to the list at the integer's index.
allowsMultipleSelections	boolean allowsMultipleSelections() Call to see if the current list lets the user select from multiple entries.
clear	void clear() Erases the current list's contents.
countItems	int countItems() Call to receive the total number of items in the list.
delItem	void delItem(int) Deletes the integer parameter's indexed item from the current list.
delItems	void delItems(int, int) Deletes the current list's items from the first parameter's index to the second parameter's index value.
deselect	void deselect(int) Deselects a selected item at the integer index.
getItem	void getItem(int) Call to get the item at the integer index.
getRows	int getRows() Call to receive the number of rows currently showing in the current list.
getSelectedIndex	int getSelectedIndex() Call to receive the currently selected item's index (getSelectedIndex() returns -1 if no items are selected).
getSelectedIndexes	int [] getSelectedIndexes() Call to receive all the indexes for the items currently selected (getSelectedIndex() returns -1 if no items are selected) for multiple selection lists.
getSelectedItem	Sting getSelectedItem() Call to receive the currently selected item (getSelectedItem() returns null if no items are selected).
getSelectedItems	String [] getSelectedItems() Call to receive all the items currently selected (getSelectedItems() returns null if no items are selected) for multiple selection lists.
getVisibleIndex	int getVisibleIndex() Call to receive the most recently-made visible item.
isSelected	boolean isSelected(int) Call to determine if the integer parameter's indexed item is selected.
makeVisible	void makeVisible(int) Brings the indexed item into view.
replaceItem	void replaceItem(String, int) Call to replace the item indicated by the integer index with the new item's string parameter.
select	void select(int) Selects the item at the integer parameter's index.
setMultipleSelections	void setMultipleSelections(boolean) Call to determine if the list will allow for multiple selections.

The java.awt.Menu Class

Use the java.awt.Menu class to create and manipulate your applet's menus that drop down from the menu bar. Use the following methods to create and manipulate your menus.

Class Method	Prototype and Description
Menu	Menu(String [, boolean]) Constructs a menu with the specified string title. If you supply a true boolean parameter, the menu is a tear-off menu, meaning that the menu remains on the screen after the user releases the mouse button.
add	MenuItem add(MenuItem) Adds an item to the current menu.
add	void add(String) Adds a new item with the string value to the current menu.
addSeparator	void addSeparator() Adds a menu separator bar to the menu.
countItems	int countItems() Call to receive the number of items in the menu.
getItem	MenuItem getItem(int) Call to receive the menu item located at the integer parameter's menu index.
isTearOff	boolean isTearOff() Call to determine if the menu is a tear-off menu.
remove	void remove(int) Removes the selected integer parameter's indexed item.
remove	void remove(MenuComponent) Removes the selected menu component from the current menu.

The java.awt.MenuBar Class

Use the java.awt.MenuBar class to create and manipulate your applet's menu bars. Use the following methods to create and manipulate your menu bars.

Class Method	Prototype and Description
MenuBar	MenuBar() Constructs a new menu bar that is unattached to any frame.
add	Menu add(Menu) Adds an item to the current menu bar.
countMenus	int countItems() Call to receive the number of items in the menu bar.
getHelpMenu	Menu getHelpMenu() Call to receive the current menu bar's help menu.
getMenu	Menu getMenu(int) Call to receive the integer index's menu bar item's menu.
remove	void remove(int) Removes the selected integer parameter's indexed item from the current menu bar.
remove	void remove(MenuComponent) Removes the selected menu component from the current menu bar.
setHelpMenu	void setHelpMenu(Menu) Indicates which menu is the Help menu on the current menu bar.

The java.awt.MenuItem Class

Use the java.awt.MenuItem class to create and manipulate your applet's individual menu items. Use the following methods to create and manipulate your menu items.

Class Method	Prototype and Description
MenuItem	MenuItem(String) Constructs a new menu item, labeled with the string parameter.
disable	void disable() Disables, or grays out, the current menu item.
enables	void enable([boolean]) Enables, or activates, the current menu item. Use the optional boolean parameter to disable or enable the item.
getLabel	String getLabel() Call to receive the current menu item's label.
isEnabled	boolean isEnabled() Call to determine if the current menu item is enabled or disabled.
setLabel	void setLabel(String) Adds the string parameter's label to the menu item.

The java.awt.Point Class

Use the java.awt.Point class to create and manipulate your applet's graphics points. The AWT class supports the following variables that define the coordinates of the given point:

Point.x The point's x-coordinate
Point.y The point's y-coordinate

Use the following methods to create and manipulate your graphics points.

Class Method	Prototype and Description
Point	Point(int, int) Constructs a new point at the integer parameter's coordinates.
equals	boolean equals(Object) Determines if the current point and the object appear at the same coordinate.
move	void move(int, int) Moves the current point to the new integer parameter coordinates.

The java.awt.Polygon Class

Use the java.awt.Polygon class to create and manipulate your applet's graphics polygons (multi-sided figures). The AWT class supports the following variables that define the coordinates of the given polygon:

Polygon.npoints The total number of points in the polygon
Polygon.xpoints The number of x-coordinate points in the polygon
Polygon.ypoints The number of y-coordinate points in the polygon

Use the following methods to create and manipulate your graphics polygons.

Class Method	Prototype and Description
Polygon	Polygon(int [], int [], int) Constructs a new polygon at the integer parameter's coordinate array pairs with the number of points specified by the third parameter.
addPoint	void addPoint(int, int) Adds a point to the current polygon.
inside	boolean inside(int, int) Call to determine if the specified coordinate point falls with the polygon's region.

The java.awt.Rectangle Class

Use the java.awt.Rectangle class to create and manipulate your applet's graphics rectangles. The AWT class supports the following variables that define the coordinates of the given rectangle:

Rectangle.height The total number of points of the rectangle's height
Rectangle.width The total number of points of the rectangle's width
Rectangle.x The rectangle's x-coordinate
Rectangle.y The rectangle's y-coordinate

Use the following methods to create and manipulate your graphics rectangles.

Class Method	Prototype and Description
Rectangle	Rectangle([int, int]) Constructs a rectangle with the optional coordinates.
Rectangle	Rectangle(int, int, int, int) Constructs a rectangle with the coordinates and the width and height specified by the last two integer parameters.
Rectangle	Rectangle(Dimension) Constructs a rectangle from the dimension passed.
add	void add(int, int) Adds a point to the current rectangle so that the rectangle has to grow to envelope the point as well as the rectangle's original size.
equals	boolean equals(Object) Call to see if the current rectangle is equal to the object's dimensions.
grow	void grow(int, int) Grows the current rectangle to twice the size of the passed coordinates while keeping the original center of the rectangle.
inside	boolean inside(int, int) Call to determine if the specified coordinate point falls with the rectangle's region.
intersects	boolean intersects(Rectangle) Call to see if the current rectangle intersects the passed rectangle.
move	void move(int, int) Moves the current rectangle to the passed coordinate pair.
reshape	void reshape(int, int, int, int) Reshapes the current rectangle to the passed x- and y-coordinates with the width and height specified by the last two integer parameters.

The java.awt.ScrollBar Class

Use the java.awt.Scrollbar class to create and manipulate your applet's graphics scrollbars. The AWT class supports the following variables that define the scrollbar:

ScrollBar.HORIZONTAL Specifies that the scrollbar is to be a horizontally-oriented scrollbar
ScrollBar.VERTICAL Specifies that the scrollbar is to be a vertically-oriented scrollbar

Use the following methods to create and manipulate your scrollbars.

Class Method	Prototype and Description
Scrollbar	Scrollbar([int]) Constructs a scrollbar with the passed orientation (use a named constant).
Scrollbar	Scrollbar(int, int, int, int, int) Constructs a scrollbar with the passed orientation, an initial value, the integer point size of the scrollbar, and the maximum and minimum scrollbar values.
getLineIncrement	int getLineIncrement() Call to receive the current scrollbar's line increment.
getMaximum	int getMaximum() Call to receive the current scrollbar's maximum value.
getMinimum	int getMinimum() Call to receive the current scrollbar's minimum value.
getOrientation	int getOrientation() Call to receive the current scrollbar's horizontal or vertical orientation.
getPageIncrement	int getPageIncrement() Call to receive the current scrollbar's page increment value.
getValue	int getValue() Call to receive the current scrollbar's current value.
getVisible	int getVisible() Call to receive the current scrollbar's visible value.
setLineIncrement	void setLineIncrement(int) Specifies the scrollbar's line increment (the amount that scrolls when the user clicks the up or down arrow).
setPageIncrement	void setPageIncrement(int) Specifies the scrollbar's page increment (the amount that scrolls when the user clicks inside the scrollbar's shaft).
setValue	void setValue(int) Sets the current scrollbar's value.
setValues	void setValues(int, int, int, int) Sets these scrollbar values: current value set, the visible amount, the minimum value, and the maximum value.

The java.awt.TextArea Class

Use the java.awt.TextArea class to create and manipulate your applet's text areas. Use the following methods to create and manipulate your text areas.

Class Method	Prototype and Description
TextArea	TextArea([int, int]) Constructs the text area with the optional number of character columns and rows.
TextArea	TextArea(String, [int, int]) Constructs the text area with an initial string value and sets to the optional number of character columns and rows.
appendText	void appendText(String) Adds the string to the end of the current text area.
getColumns	int getColumns() Call to receive the text area's columns.
getRows	int getRows() Call to receive the text area's rows.
insertText	void insertText(String, int) Inserts the string at the integer parameter's index position within the text area.
replaceText	void replaceText(String, int, int) Replaces the text area's text with the string, starting at the second parameter's index position and ending with the third parameter's index position.

The java.awt.Component Class

Use the java.awt.Component class to create and manipulate your applet's text-editing capabilities within text boxes and text areas. Use the following methods to create and manipulate your applet's text-editing capabilities.

Class Method	Prototype and Description
getSelectedText	String getSelectedText() Call to receive the currently selected text.
getSelectionEnd	int getSelectionEnd() Call to receive the currently selected text's ending index.
getSelectionStart	int getSelectionStart() Call to receive the currently selected text's starting index.
getText	String getText() Call to receive the selected text.
isEditable	boolean isEditable() Call to determine if the current text is editable.
select	void select(int, int) Select the text beginning at the first parameter's index position and ending with the second parameter's index position.
selectAll	void selectAll() Selects all the text in the text component.
setEditable	void setEditable(boolean) Specifies that the current text component is editable or not.
setText	void setText(String) Places the string text in the current text component.

The java.awt.TextField Class

Use the java.awt.TextField class to create and manipulate your applet's editable text boxes. Use the following methods to create and manipulate your applet's text boxes.

Class Method	Prototype and Description
TextField	TextField([int]) Constructs a new text box that has the optional number of columns.
TextField	TextField(String [, int]) Constructs a new text box with the string label defined to have the optional number of columns.
getColumns	int getColumns() Call to receive the number of columns in the text box.

The java.awt.Window Class

Use the java.awt.Window class to create and manipulate your applet's windows. Use the following methods to create and manipulate your applet's windows.

Class Method	Prototype and Description
Window	Window(Frame) Constructs a new modal window frame that is initially invisible.
dispose	void dispose() Destroys the window frame and releases its resources.
show	void show() Displays the current window frame.
toBack	void toBack() Sends the current window frame to the back of the window stacks.
toFront	void toFront() Brings the current window frame to the front of the window stacks.

Summary

The goal of this chapter was to list the methods and data members you may want to use from the Applet and AWT class packages. Although you may not have a need for every method discussed, this chapter does give you a reference for studying sample Java code that you view on the Internet and inside the Visual J++ sample applets.

This chapter concludes this book, but not your Visual J++ mastery. We hope that we have met and surpassed your expectations for this book; that is, we hope that you now have the tools you need to understand Visual J++'s basics, to know where Java fits into the picture, and to write your own Java-enabled Web sites with Visual J++.

Here are the points this chapter covered:

The class packages are extensive and contain numerous pre-defined class named constants and methods that you can use and subclass within your own programs.
The Applet and AWT class packages are the packages used most by Visual J++ newcomers.

You can use this chapter as a reference while continuing to hone your Visual J++ skills. When you run across a class that contains a method you don't understand, or when you need to draw a particular shape and don't know the methods needed, look to this chapter for a description of the class that performs the job.

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