Basic RootPaneContainers

For the rest of this chapter, we’ll look at some basic containers (JFrame, JWindow, and JApplet) that implement RootPaneContainer and use JRootPane. First, we’ll take a quick look at a simple interface called WindowConstants.

The WindowConstants Interface

WindowConstants is a simple interface containing only constants. It is implemented by JFrame, JDialog, and JInternalFrame.


The constants defined in WindowConstants specify possible behaviors in response to a window being closed. These values are shown in Table 8.6.

Table 8-6. WindowConstants Constants






Dispose window when closed.



Do nothing when closed.



Hide window when closed.

In the next section, we’ll look at a strategy for exiting the application in response to a frame being closed.

The JFrame Class

The most common Swing container for Java applications is the JFrame. Like java.awt.Frame, JFrame provides a top-level window with a title, border, and other platform-specific adornments (e.g., minimize, maximize, and close buttons). Because it uses a JRootPane as its only child, working with a JFrame is slightly different than working with an AWT Frame. An empty JFrame is shown in Figure 8.9.


Figure 8-9. JFrame

The primary difference is that calls to add() must be replaced with calls to ...

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