Containers. Atomic Components. Containment Hierarchy. Example Example 3.3 (revisited) Example DemoSwing.java

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1 Atomic Components Containers An atomic component is: a low-level entity an entity that interacts with the user an entity that cannot hold other components Examples: buttons (), text fields (JTextField) combo boxes (JComboBox) Other components: JFrame and Are these atomic? 58 Containers hold components All components are placed in containers Might be top-level or intermediate Top-Level E.g., JFrame is a top-level container It exists mainly as a place for other components to paint themselves Other top-level containers: dialogs (JDialog) and applets (JApplet) Intermediate E.g., is an intermediate container Its purpose is to simplify the positioning of interactive objects, such as buttons or text fields Other intermediate containers: scroll panes (JScrollPane) and tabbed panes (JTabbedPane) 59 Containment Hierarchy Example 5.11 A window is made up of a number of components atomic components (e.g.,buttons, text fields) composite components (e.g., containers) How might the relationship of these components be expressed? by a containment hierarchy based on screen geometry of objects represents the hierarchy/nesting of the objects 60 Display Screen F:\cs160\Public window Inner Window title bar horizontal scroll bar contents area CDJukebox folder Home Ent folder size control Web Newspaper window 61 Example 5.12 Display Screen Outer Win [black] Inner Win [green] Result Win [tan] Result String Keypad [Teal] = button - button = ENT + button 62 0 button Example 3.3 (revisited) DemoSwing.java How to determine the containment hierarchy? Keystroke combination: CTRL-SHIFT-F1 63

2 Example 3.3 (revisited) DemoSwing.java DemoSwingFrame[frame0,0,0,224x208,... javax.swing.jrootpane[,4,23,216x181,... javax.swing.[null.glasspane,... javax.swing.jlayeredpane[null.layeredpane,0,0,216x181,... javax.swing.[null.contentpane,0,0,216x181,... javax.swing.[,0,0,216x181,... javax.swing.[,50,50,116x27,... javax.swing.jlabel[,50,77,116x27,... javax.swing.[,50,104,116x27,... E.g. javax.swing.[,50,104,116x27, layout=javax.swing.overlaylayout, alignmentx=0.0,alignmenty=0.5, flags=296,maximumsize=, minimumsize=,preferredsize=,defaulticon=, disabledicon=,disabledselectedicon=, margin=javax.swing.plaf.insetsuiresource[top=2,left=14,bottom=2,right=14], paintborder=true,paintfocus=true,pressedicon=, rolloverenabled=false, rollovericon=, rolloverselectedicon=,selectedicon=, text=exit, defaultcapable=true] 64 Example 3.3 (revisited) DemoSwing.java JLabel JFrame Root Pane Layered Pane Content Pane (container) 65 Java s Containment Hierarchy Example 5.14 In JFC/Swing, what is the basic building block for a window? The JFrame Atomic component (text field) Title JFrame content pane *** Content Pane is most important for our purposes 66 Atomic component (buttons) = ENT 67 Containment Hierarchy for JFC/Swing Outline JFrame Content pane etc. Windows Icons Menus Pointers JTextField JLabel etc. Window Managers More Widgets 68 69

3 Validating Input Examples 5.15, 5.16 JTextField provides one mechanism by which user can input data What type of information might users provide? Examples: Numeric value (e.g., weight, age) Values belong to a continuum Acceptable values fall within a range Postal or zip code Date, time How to handle input? Should it be in the format required by the application? The distinction between valid and invalid data Semantic Error vs. Format Error When to Intervene: Solicit Input Accept Proceed to next step Feedback: popup message, generate audio alarm, system behaviour DemoInputValidation1.java DemoInputValidation2.java Navigation Example 5.17 The process of moving from one component to the next Applies to both displayed and non-displayed components Recall: The attribute of being in focus or not is a state (an attribute of all components) Feedback re: currently active component given to user e.g., I-beam cursor, special highlighting Options for Navigation Pointer: Click Keyboard: Tabor Enter Desired Behaviour: advance focus to the selected component Before leaving current field, should entry be accepted and validated? Should sequence pf next focus be determined by application or user? DemoTextField.java Editable Combo Boxes Like a combo box, except allows the user to directly type in an entry Much more complicated due to Validating input Navigation Example 5.18 DemoComboBox2.java Similar to DemoComboBox.java (Example 4.5), except uses an editable combo box to specify font size

4 Toolbars Example 5.19 Recall (Module 4, slide 13): A collection of buttons typically arranged in a row or column The collection is persistent Appropriate for commonly used functions Provide convenient access to common menu commands(contrast with menus) Meaning typically signaled by an icon rather than text DemoToolBar.java Commands are displayed (requires recognize rather than recall ), but this requires display space Tool Tips Tool Tips A tool tip: a small text field that pops up when the cursor pauses over a GUI component What should the text do? provides a terse description of the command associated with, or the purpose of, the component be a supplement to the text or icon label 78 Advantages Aids in command recognition Does not consume screen space until shown Disadvantages Can t be selective Can occlude other components Terse wording may be inadequate Frequent changes in appearance/disappearance annoying to some users 79 Example 5.19 (revisited) Sliders DemoToolBar.java Device for soliciting input domain of input values must correspond to a pseudo- continuous variable Examples RGB values in a color chooser Time delays for animations NB: cursor not captured by screen capture utility 80 81

5 Example 5.20 Example 5.21 DemoSliderBB.java DemoSlider.java Scrollbars Example 5.22 Anatomy: DemoScrollBarBB.java Arrow button Track Elevator (aka Knob) Arrow button Viewports and Scrollable Clients Example 5.23 DemoScrollPane.java Source: JScrollPane API Specification 86 87

6 Example 5.24 JList DemoScrollPane2.java A component that allows a user to select one or more items from a list Example 5.25 Example 5.26 DemoList.java DemoListMultiple.java JTable Example 5.27 A component that displays regular twodimensional tables of cells entries can be edited DemoTable.java 92 93

7 Dialog Boxes File Chooser Color Chooser Custom Dialog Box Example 5.28 DemoFileChooser.java Example 5.29 Example 5.30 DemoMenu2.java DemoCustomDialog.java 96 97