Components

Controls

Methods / Description

Size

Dimension getSize()

void setSize(int width, int height)

void setSize(Dimension d)

Location

Point getLocation()

void setLocation(int x, int y)

void setLocation(Point p)

Size and Location

Rectangle getBounds()

void setBounds (int x, int y, int width, int height)

void setBounds (Rectangle r)

Color

void setForeground(Color c)

void setBackground(Color c)

Font

void setFont(Font f)

void setFont(Font f)

Visibility and Enabling

void setEnabled(boolean b)

void setVisible(boolean b)

Container

Description

Panel

·         Provides intermediate level of spatial organization and containment.

·         Not a top-level window

·         Does not have title, border or menubar.

·         Can be recursively nested.

·         Default layout is Flow layout.

Applet

·         Specialized Panel, run inside other applications (typically browsers)

·         Changing the size of an applet is allowed or forbidden depending on the browser.

·         Default layout is Flow layout.

Window

·         Top-level window without a title, border or menus.

·         Seldom used directly. Subclasses (Frame and Dialog) are used.

·         Defines these methods:

·         void pack() – Initiates layout management, window size might be changed as a result

·         void show() – Makes the window visible, also brings it to front

·         void dispose() – When a window is no longer needed, call this to free resources.

Frame

·         Top-level window (optionally user-resizable and movable) with a title-bar, an icon and menus.

·         Typically the starting point of a GUI application.

·         Default layout is Border layout.

Dialog

·         Top-level window (optionally user-resizable and movable) with a title-bar.

·         Doesn’t have icons or menus.

·         Can be made modal.

·         A parent frame needs to be specified to create a Dialog.

·         Default layout is Border layout.

ScrollPane

·         Can contain a single component. If the component is larger than the scrollpane, it acquires vertical / horizontal scrollbars as specified in the constructor.

·         SCROLLBARS_AS_NEEDED – default, if nothing specified

·         SCROLLBARS_ALWAYS

·         SCROLLBARS_NEVER

Component

Description

Constructors

Events

Button

·         A button with a textual label.

new Button(“Apply”)

Action event.

Canvas

·         No default appearance.

·         Can be sub-classed to create custom drawing areas.

Mouse, MouseMotion, Key events.

Checkbox

·         Toggling check box.

·         Default initial state is false.

·         getState(), setState(boolean state) - methods

·         Can be grouped with a CheckboxGroup to provide radio behavior.

·         Checkboxgroup is not a subclass of Component.

·         Checkboxgroup provides these methods: getSelectedCheckbox and setSelectedCheckbox(Checkbox new)

Checkbox(String label)

Checkbox(String label, boolean initialstate)

Checkbox(String label, CheckBoxGroup group)

Item event

Choice

·         A pull-down list

·         Can be populated by repeatedly calling addItem(String item) method.

·         Only the current choice is visible.

Item event

FileDialog

·         Subclass of Dialog

·         Open or Save file dialog, modal

·         Dialog automatically removed, after user selects the file or hits cancel.

·         getFile(), getDirectory() methods can be used to get information about the selected file.

FileDialog(Frame parent, String title, int mode)

Mode can be FileDialog.LOAD or

FileDialog.SAVE

Label

·         Displays a single line of read-only non-selectable text

·         Alignment can be

Label.LEFT, Label.RIGHT or Label.CENTER

Label()

Label(String label)

Label(String label, int align)

None

List

·         Scrollable vertical list of text items.

·         No of visible rows can be specified, if not specified layout manager determines this.

·         Acquires a vertical scrollbar if needed.

·         List class methods:

· addItem(String), addItem(String, int index)

· getItem(int index), getItemCount()

· getRows() – no of visible rows

· int getSelectedIndex()

· int[] getSelectedIndexes()

· String getSelectedItem()

· String[] getSelectedItems()

List()

List(int nVisibleRows)

List(int nVisibleRows, boolean multiSelectOK)

Item event – selecting or deselecting

Action event – double clicking

Scrollbar

·         With the last form of constructor, calculate the spread as maxvalue – minvalue. Then the slider width is slidersize / spread times of scrollbar width.

Scrollbar() – a vertical scrollbar.

Scrollbar(int orientation)

Scrollbar(int orientation, int initialvalue, int slidersize, int minvalue, int maxvalue)

Orientation can be

Scrollbar.HORIZONTAL

Scrollbar.VERTICAL

Adjustment event

TextField

·         Extends TextComponent

·         Single line of edit / display of text.

·         Scrolled using arrow keys.

·         Depending on the font, number of displayable characters can vary.

·         But, never changes size once created.

·         Methods from TextComponent:

·         String getSelectedText()

·         String getText()

·         void setEditable(boolean editable)

·         void setText(String text)

TextField() – empty field

TextField(int ncols) – size

TextField(String text) – initial text

TextField(String text, int ncols) – initial text and size

Text event

Action event – Enter key is pressed.

TextArea

·         Extends TextComponent

·         Multiple lines of edit/display of text.

·         Scrolled using arrow keys.

·         Can use the TextComponent methods specified above.

·         Scroll parameter in last constructor form could be

TextArea.SCROLLBARS_BOTH, TextArea.SCROLLBARS_NONE, TextArea.SCROLLBARS_HORIZONTAL_ONLY

TextArea.SCROLLBARS_VERTICAL_ONLY

TextArea() – empty area

TextArea(int nrows, int ncols) – size

TextArea(String text) – initial text

TextArea(String text, int nrows, int ncols) – initial text and size

TextArea(String text, int nrows, int ncols, int scroll)

Text event