Download - Unit 131 GUI Layout Managers and Components, Continue Card Layout Borders More GUI components Menu List Sliders Combo Boxes Scroll Panes Split Panes Special.

Unit 13 1

GUI Layout Managers and Components, Continue

• Card Layout

• Borders

• More GUI components• Menu

• List

• Sliders

• Combo Boxes

• Scroll Panes

• Split Panes

• Special Features of Swing components

• Further GUI Programming Examples

• Exercises

Unit 13 2

Introduction

• This is our concluding session on GUIs and event-driven programming.

• In our discussion on GUI-based programs so far, we have covered:

– GUI design issues, GUI components and containers.

– Basic event handling.

– Basic layout management.

• We are going to cover:

• More GUI components.

• More layout managers.

• Special Features of Swing components

• With this coverage the student's knowledge base of the basics would be broadened.

Unit 13 3

• A CardLayout object is a layout manager for a container. It treats each component in the container as a card.

• Only one card is visible at a time, and the container acts as a stack of cards.

• The first component added to a CardLayout object is the visible component when the container is first displayed.

• The ordering of cards is determined by the container's own internal ordering of its component objects.

• CardLayout defines a set of methods that allow an application to flip through these cards sequentially, or to show a specified card.

• Card Layout has two constructors:• CardLayout(): Creates a new card layout with gaps of size zero.• CardLayout(int hgap, int vgap) Creates a new card layout with

the specified horizontal and vertical gaps.

Card Layout Manager

Unit 13 4

Card Layout

• Use the Card Layout class when you have an area that can contain

different components at different times.

• Panel cards = new Panel();

• CardLayout cardLayout = new CardLayout();

• cards.setLayout(cardLayout);

• cards.add("Ace", new Button("Ace of Hearts"));

• cards.add("Deuce", new Button("Two of Hearts"));

• cards.add("Three", new Button("Three of Hearts"));

Unit 13 5

Introduction to Borders

• A border can be put around any Swing component to define how the edges of the component should be drawn.

• The BorderFactory class is useful for creating border objects.

• It has methods for creating specific types of borders.

• A border is applied to a component using the setBorder method:

JPanel myPanel = new JPanel();

Border myBorder = BorderFactory.createEtchedBorder();

myPanel.setBorder(myBorder);

Unit 13 6

Borders

• A line border

– Surrounds the component with a simple line

– The line's color and thickness can be specified

• An etched border

– Creates the effect of an etched groove around a component

– Uses colors for the highlight and shadow

• A bevel border

– Can be raised or lowered

– Uses colors for the outer and inner highlights and shadows

Unit 13 7

Borders

• A compound border

– Is a combination of two borders

– One or both of the borders can be a compound border

• A titled border

– Places a title on or around the border

– The title can be oriented in many ways

• A matte border

– Specifies the sizes of the top, left, bottom, and right edges of the border separately

– Uses either a solid color or an image.

Unit 13 8

The BorderDemo Program

Unit 13 9

MenuBar and Menu

• A menu offers options to user.• Menus are not generally added to user interface.• Menu usually appears either in a menu bar or as a popup

menu.• A JFrame often has a menu bar containing many menus;

and each menu can contain many choices.• Menu bar can be added to a JFrame with the method

setJMenuBar.

JFrame window = new JFrame("Some Application");

JMenuBar menuBar = new JMenuBar();

window.setJMenuBar(menuBar);

Unit 13 10

Menu

• Menus are JMenu instances and added to menu bar:

JMenu batter = new JMenu("Batter");

menuBar.add(batter);

• Menu choices are JMenuItem instances, and are added to menu:

JMenuItem swing = new JMenuItem("Swing");

JMenuItem take = new JMenuItem("Take");

JMenuItem bunt = new JMenuItem("Bunt");

batter.add(swing);

batter.add(take);

batter.add(bunt);

Unit 13 11

Lists

• The Swing Jlist class represents a list of items from which the user can choose.

• The contents of a JList object can be specified using an array of objects.

• A JList object generates a list selection event when the current selection changes.

• A JList object can be set so that multiple items can be selected at the same time. It can be one of three options:

– Single selection – only one item can be selected at a time.– Single interval selection – multiple, contiguous items can be selected

at a time.– Multiple interval selection – any combination of items can be

selected.

• The list selection mode is defined by a ListSelectionModel object.

Unit 13 12

Declaring a JList

String[] items = {“A", “B", “C", "D"};

JList list = new JList(items);

list.setSelectionMode(DefaultListSelectionModel.SINGLE_SELECTION);

// Set the item width

int cellWidth = 200;

list.setFixedCellWidth(cellWidth);

// Set the item height

int cellHeight = 18;

list.setFixedCellHeight(cellHeight);

// Get number of items

in the list int size = list.getModel().getSize();

Unit 13 13

List Example

Frame frame = new Frame(); frame.setLayout(new FlowLayout()); Button button1 = new Button("Next"); frame.add(button1); TextField text1 = new TextField(); text1.setColumns(10); frame.add(text1); Label label1 = new Label("First Name:"); frame.add(label1); TextArea textArea1 = new TextArea("This is some text in a text area"); textArea1.setRows(2); textArea1.setColumns(10); frame.add(textArea1); List list1 = new List(); list1.add("FirstItem"); list1.add("SecondItem"); list1.add("ThirdItem"); list1.add("FourthItem"); list1.add("FifthItem"); frame.add(list1); frame.pack(); frame.setVisible(true);

Unit 13 14

Sliders

• A slider is a component that allows the user to specify a numeric value within a bounded range.

• The JSlider class has several methods that allow the programmer to tailor the look of a slider.

• Major and minor tick marks, and labels on the tick marks, can be explicitly set and displayed.

• A slider produces a change event.

Unit 13 15

Sliders Declaration

// Create a horizontal slider with min=0, max=100, value=50

JSlider slider = new JSlider();

// Create a horizontal slider with custom min and max; value is set to the middle

int minimum = -255;

int maximum = 256;

slider = new JSlider(minimum, maximum);

// Create a horizontal slider with custom min, max, and value

int initValue = 0;

slider = new JSlider(minimum, maximum, initValue);

// Create a vertical slider with min=0, max=100, value=50

slider = new JSlider(JSlider.VERTICAL);

// Create a vertical slider with custom min, max, and value

slider = new JSlider(JSlider.VERTICAL, minimum, maximum, initValue);

Unit 13 16

Combo Boxes

• A combo box provides a menu from which the user can choose one of several options.

• The currently selected option is shown in the combo box.

• Unlike a JList object, a combo box shows its options only when the user presses it using the mouse.

• Options can be established using an array of strings or using the addItem method.

• A combo box generates an action event when the user makes a selection from it.

// Create a read-only combobox

String[] items = {"item1", "item2"};

JComboBox readOnlyCB = new JComboBox(items);

// Create an editable combobox

items = new String[]{"item1", "item2"};

JComboBox editableCB = new JComboBox(items);

editableCB.setEditable(true);

Unit 13 17

Scroll Panes

• A scroll pane is useful for images or information too large to fit in a reasonably-sized area.

• A scroll pane offers a limited view of the component it contains.

• It provides vertical and/or horizontal scroll bars that allow the user to scroll to other areas of the component.

• No event listener is needed for a scroll pane.

// Create a scrollable text area

JTextArea textArea = new JTextArea();

JScrollPane scrollableTextArea = new JScrollPane(textArea);

// Create a scrollable list

JList list = new JList();

JScrollPane scrollableList = new JScrollPane(list);

Unit 13 18

Split Panes

• A split pane (JSplitPane) is a container that displays two components separated by a moveable divider bar

• The two components can be displayed side by side, or one on top of the other.

Moveable Divider Bar

LeftComponent

RightComponent

Top Component

Bottom Component

Unit 13 19

Split Panes

• The orientation of the split pane is set using the HORIZONTAL_SPLIT or VERTICAL_SPLIT constants

• The divider bar can be set so that it can be fully expanded with one click of the mouse.

• The components can be continuously adjusted as the divider bar is moved, or wait until it stops moving.

• Split panes can be nested

// Create a left-right split pane

JSplitPane hpane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftComponent, rightComponent);

// Create a top-bottom split pane

JSplitPane vpane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, topComponent, bottomComponent);

Unit 13 20

Special Features

• Swing components offer special features to facilitate and enhance their use

Special Feature Description

Tool tip Causes a line of text to appear when the mouse cursor pauses over a component

Mnemonic Allows an action to occur in response to a keyboard key combination

Disable Allows a component to be explicitly enabled or disabled

Border Surrounds a component with a border

Unit 13 21

Tool Tips

• Tool tips provide a short pop-up description when the mouse cursor rests momentarily on a component

• A tool tip is assigned using the setToolTipText method of a Swing component.

JButton button = new JButton ("Compute");

button.setToolTipText ("Calculate size.");

Unit 13 22

Disabled Components

• Components can be disabled if they should not be used.

• A disabled component is "grayed out" and will not respond to user interaction.

• The status is set using the setEnabled method:

JButton button = new JButton (“Do It”);

button.setEnabled (false);