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Java in a Nutshell

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The java.awt Package
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18.36 java.awt.LayoutManager (JDK 1.0)

This interface defines the methods necessary for a class to be able to arrange Component objects within a Container object. Most programs use one of the existing classes that implements this interface: BorderLayout, CardLayout, FlowLayout, GridBagConstraints, GridBagLayout, or GridLayout.

To define a new class that lays out components, you must implement each of the methods defined by this interface. addLayoutComponent() is called when a component is added to the container. removeLayoutComponent() is called when a component is removed. layoutContainer() should perform the actual positioning of components by setting the size and position of each component in the specified container. minimumLayoutSize() should return the minimum container width and height that the LayoutManager needs in order to lay out its components. preferredLayoutSize() should return the optimal container width and height for the LayoutManager to lay out its components.

In Java 1.1, layout managers should implement the LayoutManager2 interface, which is an extension of this one. Note that a Java applet or application never directly calls any of these LayoutManager methods--the Container object for which the LayoutManager is registered does that.

public abstract interface LayoutManager {
    // Public Instance Methods
            public abstract void addLayoutComponent(String name, Component comp);
            public abstract void layoutContainer(Container parent);
            public abstract Dimension minimumLayoutSize(Container parent);
            public abstract Dimension preferredLayoutSize(Container parent);
            public abstract void removeLayoutComponent(Component comp);
}

Extended By:

LayoutManager2

Implemented By:

FlowLayout, GridLayout

Passed To:

Container.setLayout(), Panel(), ScrollPane.setLayout()

Returned By:

Container.getLayout()


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