![]() ![]() ![]() Like other containers, a panel uses a layout manager to position and size its components. The rest of this section gives hints on grouping and laying out components. Here is what the Converter application normally looks like.Īs the Converter example demonstrates, panels are useful for grouping components, simplifying component layout, and putting borders around groups of components. Each of these JPanel instances uses a top-to-bottom BoxLayout object to lay out its contents. In each ConversionPanel, an instance of an unnamed JPanel subclass colored blue groups two components (a text field and a slider) and restricts their size.Each of these JPanel instances uses a top-to-bottom BoxLayout object (helped by an invisible space-filling component) to lay out the combo box. In each ConversionPanel, a JPanel instance colored magenta is used to ensure the proper size and position of the combo box.Each ConversionPanel panel uses a left-to-right BoxLayout object to lay out its contents. These ConversionPanel panels also have titled borders, which describe their contents and enclose the contents with a line. Two instances of a custom JPanel subclass named ConversionPanel colored cyan are used to contain components and coordinate communication between components.See Using Top-Level Containers for information about content panes. This content pane uses a top-to-bottomīoxLayout to lay out its contents, and an empty border to put 5 pixels of space around them. One JPanel instance colored red in the preceding snapshot serves as a content pane for the application's frame.The Converter example uses panels in several ways: The following picture shows a colored version of the Converter application, which is discussed in more detail in Using Models. A transparent panel draws no background, so that any components underneath show through. You can change a panel's transparency by invoking the setOpaque method. Opaque panels work well as content panes and can help with painting efficiently, as described in In many types of look and feel, panels are opaque by default. By default, panels do not add colors to anything except their own background however, you can easily add borders to them and otherwise customize their painting. JPanel class provides general-purpose containers for lightweight components. ![]()
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