FileDocCategorySizeDatePackage
Popup.javaAPI DocJava SE 5 API7201Fri Aug 26 14:57:58 BST 2005javax.swing

Popup

public class Popup extends Object
Popups are used to display a Component to the user, typically on top of all the other Components in a particular containment hierarchy. Popups have a very small life cycle. Once you have obtained a Popup, and hidden it (invoked the hide method), you should no longer invoke any methods on it. This allows the PopupFactory to cache Popups for later use.

The general contract is that if you need to change the size of the Component, or location of the Popup, you should obtain a new Popup.

Popup does not descend from Component, rather implementations of Popup are responsible for creating and maintaining their own Components to render the requested Component to the user.

You typically do not explicitly create an instance of Popup, instead obtain one from a PopupFactory.

see
PopupFactory
version
1.17 12/19/03
since
1.4

Fields Summary
private Component
component
The Component representing the Popup.
Constructors Summary
protected Popup(Component owner, Component contents, int x, int y)
Creates a Popup for the Component owner containing the Component contents. owner is used to determine which Window the new Popup will parent the Component the Popup creates to. A null owner implies there is no valid parent. x and y specify the preferred initial location to place the Popup at. Based on screen size, or other paramaters, the Popup may not display at x and y.

param
owner Component mouse coordinates are relative to, may be null
param
contents Contents of the Popup
param
x Initial x screen coordinate
param
y Initial y screen coordinate
exception
IllegalArgumentException if contents is null

        this();
        if (contents == null) {
            throw new IllegalArgumentException("Contents must be non-null");
        }
        reset(owner, contents, x, y);
protected Popup()
Creates a Popup. This is provided for subclasses.
Methods Summary
java.awt.ComponentcreateComponent(java.awt.Component owner)
Creates the Component to use as the parent of the Popup. The default implementation creates a Window, subclasses should override.

        if (GraphicsEnvironment.isHeadless()) {
            // Generally not useful, bail.
            return null;
        }
        return new HeavyWeightWindow(getParentWindow(owner));
voiddispose()
Frees any resources the Popup may be holding onto.

        Component component = getComponent();

        if (component instanceof JWindow) {
            ((Window)component).dispose();
            component = null;
        }
java.awt.ComponentgetComponent()
Returns the Component returned from createComponent that will hold the Popup.

        return component;
private java.awt.WindowgetParentWindow(java.awt.Component owner)
Returns the Window to use as the parent of the Window created for the Popup. This creates a new Frame each time it is invoked. Subclasses that wish to support a different Window parent should override this.

        Window window = null;

        if (owner instanceof Window) {
            window = (Window)owner;
        }
        else if (owner != null) {
            window = SwingUtilities.getWindowAncestor(owner);
        }
        if (window == null) {
            window = new DefaultFrame();
        }
        return window;
public voidhide()
Hides and disposes of the Popup. Once a Popup has been disposed you should no longer invoke methods on it. A disposed Popup may be reclaimed and later used based on the PopupFactory. As such, if you invoke methods on a disposed Popup, indeterminate behavior will result.

        Component component = getComponent();

        if (component instanceof JWindow) {
            component.hide();
            ((JWindow)component).getContentPane().removeAll();
        }
        dispose();
voidpack()
Causes the Popup to be sized to fit the preferred size of the Component it contains.

        Component component = getComponent();

        if (component instanceof Window) {
            ((Window)component).pack();
        }
voidreset(java.awt.Component owner, java.awt.Component contents, int ownerX, int ownerY)
Resets the Popup to an initial state.

        if (getComponent() == null) {
            component = createComponent(owner);
        }

        Component c = getComponent();

        if (c instanceof JWindow) {
            JWindow component = (JWindow)getComponent();

            component.setLocation(ownerX, ownerY);
            component.getContentPane().add(contents, BorderLayout.CENTER);
            contents.invalidate();
            if(component.isVisible()) {
                // Do not call pack() if window is not visible to
                // avoid early native peer creation
                pack();
            }
        }
public voidshow()
Makes the Popup visible. If the Popup is currently visible, this has no effect.

        Component component = getComponent();

        if (component != null) {
            component.show();
        }