Tell the layout manager when components are added and removed from the container.Ask for sizing information for the layout manager and the components it manages.LayoutManager is an interface in the Java class libraries that describes how a Container and a layout manager communicate. This allows a layout algorithm to be reused for several applications, while simplifying your application code.
#Make flowlayout but fill vertically code#
Rather than building the layout algorithms into your code and watching for window resizing and other layout-modifying events, the algorithm is kept separate. (I had a student from Germany who started laughing when I showed that button and told me what it meant…)Ī layout manager encapsulates an algorithm for positioning and sizing of GUI components. The user doesn’t see the entire phrase, but even worse….
Auf Wiedersehen gets chopped to the much smaller Wieder. The programmer didn’t give much thought to translations into other languages… For example:Ī simple button to end an application. However, most words have varying lengths depending on which language you are using. “No” is a good example, as it’s spelled that way in several languages. Some words take up the same amount of space in different languages. Switching font sizes will have a similar effect.Ĭomponents Designed for a Specific Language Notice that the MotifLookAndFeeluses a wider, empty border around the buttons, causing some undesirable drawing effects. The following picture shows the above GUI under the MotifLookAndFeelof the JFC Project Swing technology without using a layout manager:
Unfortunately, the programmer who wrote this application used absolute positioning and sizing, so the components in the dialog do not expand:Īfter reporting this behavior, the developer realizes the error that has been committed and changes the GUI to resize properly:Ĭomponents Designed for a Specific Look-And-Feel or Font SizeĪnother common problem is expecting all platforms or LookAndFeel libraries (when using Java Foundation Classes (JFC) Project Swing technology) to have the same sizing characteristics. In the hopes of seeing the entire name at once, you could expand the dialog horizontally. For example, in the initial display of a screen, the name entered is rather long, so it doesn’t quite fit in the text field such that all is visible at once: Non-resizable GUIs can be extremely frustrating. However, some users have much more screen real estate and want to take advantage of it. The most common display size is probably still 640x480, so it’s a good idea to make sure your application fits on that size screen. The first layout sin is to ignore a user-resize. These describe several_GUI sins_that are all too common: To describe why layout managers are necessary, all you need to do is examine a few of the problems they solve. This module will explore in great detail how the standard Abstract Window Toolkit (AWT) layout managers perform their jobs and how they can be effectively nested to create useful graphical user interfaces (GUIs). I used the Wayback Machine to retrieve it and post it here) (I wrote this article for the Sun Java Developer Connection website around 1998 and is no longer available. Let’s get familiar with Java Layout Managers!
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