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A content pane provides functionality that allows different types of components to work together in Project Swing. Because the layout manager controls the layout of components, it is set on the content pane where the components reside. Components are not added directly to a JFrame, but to its content pane. The call to the getContentPane method of the JFrame class is for adding the Panel to the JFrame.
#Java user interface builder neon how to
To find out about some of the other available layout managers and how to use them, see the JDC article Exploring the AWT Layout Managers. Specify layout manager and background color The private boolean instance variable is visible only to the SwingUI class and is used in the actionPerformedmethod to find out whether or not the button has been clicked. In this example, they are built in the SwingUI constructor and accessed in the actionPerformed method implementation. These are instance variables that can be accessed by any method in the instantiated class. These next lines declare the Project Swing component classes the SwingUI class uses. Fortunately, there is only one, actionPerformed, which is discussed below. This means the SwingUI class must implement all methods defined in the ActionListener interface. The rest of the SwingUI class declaration indicates that this class will implement the ActionListener interface. An interface defines a set of methods, but does not implement them. The Java APIs provide classes and interfaces for you to use.
#Java user interface builder neon full
Project Swing extends the AWT with a full set of GUI components and services, pluggable look and feel capabilities, and assistive technology support. The JFrame class extends the Frame class that is part of the Abstract Window Toolkit (AWT) APIs. You could replace four of these lines with this one line: import java.awt.*, to import the entire awt package, but doing that increases compilation overhead than importing exactly the classes you need and no others. The lines indicate exactly which Java API classes the program uses. At the top, you have four lines of import statements. Click again and you are back to the original window on the left. The window on the left appears when you start the application, and the window on the right appears when you click the button.
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The Project Swing code that follows builds this simple application. A frame object is a top-level window that provides a title, banner, and methods to manage the appearance and behavior of the window. In contrast to the applet in Lesson 3 where the user interface is attached to a panel object nested in a top-level browser, the Project Swing application in this lesson attaches its user interface to a panel object nested in a top-level frame object.