Java™ Application Development on Linux - Dator

374Chapter 16Getting in the Swing of Things: Designing a GUI for BudgetPro• Containers to hold GUI objects, such as JFrame for our outermost window,JPanel for an assortment of objects, and JScrollPane for viewinglarger objects through a scrollable window.• Labels (JLabel class) to hold either a short bit of text, or an image, orboth; it can even take snippets of HTML, for fancier formatting andcoloring of text.• Buttons (JButton class) to which we attached actions—the code fragmentsthat get called when the buttons get pushed; a button could havetext and/or an image displayed in it.• Actions—whether for buttons or selections (or other triggers yet to bediscussed), an action is the code that runs when the event (e.g., buttonpress) occurs.• Text fields (JTextField class) to take small amounts of user input; ourapplication didn’t need the other types of text fields (JTextArea andJTextPane) useful for much more extensive user input.•A JTable instance and its associated TableModel, SelectionModel, andTableCellRenderer which provide tremendous flexibility and controlover table behavior and contents.•A JDialog instance with custom content, to allow for multiple user inputs;the dialog comes and goes with its visibility; since it’s a modal dialog,when it is visible, it “hogs” all the user interactions; it is possible to makenonmodal dialogs, but our application didn’t need to.• LayoutManagers for our JFrame and JPanels, used to place objectswithin a container with various algorithms for placement and expansion.16.9WHAT YOU STILL DON’T KNOWOne could spend a career learning the vagaries of layout managers, especiallythe way they interact (e.g., a BoxLayout inside the various regions of aBorderLayout). There is still an art to getting all the interactions right; it’soften quickest to prototype the layout before you get too committed to a particularlayout. Also, putting objects into containers can help you subdivide thelayout problem into more manageable pieces. You can even go so far as to writeyour own LayoutManager, a topic we do not cover in this book.The information that we display in the JTable in our example is hierarchical.Swing provides a JTree object for displaying such information. Like a