The JProgressBar Class

Swing makes it easy to create progress bars. Applications typically use progress bars to report the status of time-consuming jobs, such as software installation or large amounts of copying. The bars themselves are simply rectangles of an arbitrary length, a percentage of which is filled based on the model’s value. Swing progress bars come in two flavors: horizontal and vertical. If the orientation is horizontal, the bar fills from left to right. If the bar is vertical, it fills from bottom to top. SDK 1.4 added the ability to show indeterminate progress (progress when you don’t know the total). The class hierarchy is illustrated in Figure 6-13.

JProgressBar class diagram

Figure 6-13. JProgressBar class diagram

Different L&Fs can contain different filling styles. Metal, for example, uses a solid fill, while the Windows L&F uses an LCD style, which means that the bar indicates progress by filling itself with dark, adjacent rectangles instead of with a fluid line (at the opposite extreme, the Mac’s is so fluid that it even contains moving ripples). The JProgressBar class also contains a boolean property that specifies whether the progress bar draws a dark border around itself. You can override this default border by setting the border property of the JComponent. Figure 6-14 shows a Swing progress bar with the different L&Fs.

Figure 6-14. Progress bars in various L&Fs


The basic properties ...

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