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	/*
	* Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package javax.swing;

	import java.awt.*;

	import javax.swing.plaf.*;
	import javax.accessibility.*;

	import java.io.Serializable;
	import java.io.ObjectOutputStream;
	import java.io.ObjectInputStream;
	import java.io.IOException;


	/**
	* <code>JPanel</code> is a generic lightweight container.
	* For examples and task-oriented documentation for JPanel, see
	* <a
	href="https://docs.oracle.com/javase/tutorial/uiswing/components/panel.html">How to Use Panels</a>,
	* a section in <em>The Java Tutorial</em>.
	* <p>
	* <strong>Warning:</strong> Swing is not thread safe. For more
	* information see <a
	* href="package-summary.html#threading">Swing's Threading
	* Policy</a>.
	* <p>
	* <strong>Warning:</strong>
	* Serialized objects of this class will not be compatible with
	* future Swing releases. The current serialization support is
	* appropriate for short term storage or RMI between applications running
	* the same version of Swing. As of 1.4, support for long term storage
	* of all JavaBeans™
	* has been added to the <code>java.beans</code> package.
	* Please see {@link java.beans.XMLEncoder}.
	*
	* @beaninfo
	* description: A generic lightweight container.
	*
	* @author Arnaud Weber
	* @author Steve Wilson
	*/
	public class JPanel extends JComponent implements Accessible
	{
	/**
	* @see #getUIClassID
	* @see #readObject
	*/
	private static final String uiClassID = "PanelUI";

	/**
	* Creates a new JPanel with the specified layout manager and buffering
	* strategy.
	*
	* @param layout the LayoutManager to use
	* @param isDoubleBuffered a boolean, true for double-buffering, which
	* uses additional memory space to achieve fast, flicker-free
	* updates
	*/
	public JPanel(LayoutManager layout, boolean isDoubleBuffered) {
	setLayout(layout);
	setDoubleBuffered(isDoubleBuffered);
	setUIProperty("opaque", Boolean.TRUE);
	updateUI();
	}

	/**
	* Create a new buffered JPanel with the specified layout manager
	*
	* @param layout the LayoutManager to use
	*/
	public JPanel(LayoutManager layout) {
	this(layout, true);
	}

	/**
	* Creates a new <code>JPanel</code> with <code>FlowLayout</code>
	* and the specified buffering strategy.
	* If <code>isDoubleBuffered</code> is true, the <code>JPanel</code>
	* will use a double buffer.
	*
	* @param isDoubleBuffered a boolean, true for double-buffering, which
	* uses additional memory space to achieve fast, flicker-free
	* updates
	*/
	public JPanel(boolean isDoubleBuffered) {
	this(new FlowLayout(), isDoubleBuffered);
	}

	/**
	* Creates a new <code>JPanel</code> with a double buffer
	* and a flow layout.
	*/
	public JPanel() {
	this(true);
	}

	/**
	* Resets the UI property with a value from the current look and feel.
	*
	* @see JComponent#updateUI
	*/
	public void updateUI() {
	setUI((PanelUI)UIManager.getUI(this));
	}

	/**
	* Returns the look and feel (L&amp;F) object that renders this component.
	*
	* @return the PanelUI object that renders this component
	* @since 1.4
	*/
	public PanelUI getUI() {
	return (PanelUI)ui;
	}


	/**
	* Sets the look and feel (L&F) object that renders this component.
	*
	* @param ui the PanelUI L&F object
	* @see UIDefaults#getUI
	* @since 1.4
	* @beaninfo
	* bound: true
	* hidden: true
	* attribute: visualUpdate true
	* description: The UI object that implements the Component's LookAndFeel.
	*/
	public void setUI(PanelUI ui) {
	super.setUI(ui);
	}

	/**
	* Returns a string that specifies the name of the L&F class
	* that renders this component.
	*
	* @return "PanelUI"
	* @see JComponent#getUIClassID
	* @see UIDefaults#getUI
	* @beaninfo
	* expert: true
	* description: A string that specifies the name of the L&F class.
	*/
	public String getUIClassID() {
	return uiClassID;
	}


	/**
	* See readObject() and writeObject() in JComponent for more
	* information about serialization in Swing.
	*/
	private void writeObject(ObjectOutputStream s) throws IOException {
	s.defaultWriteObject();
	if (getUIClassID().equals(uiClassID)) {
	byte count = JComponent.getWriteObjCounter(this);
	JComponent.setWriteObjCounter(this, --count);
	if (count == 0 && ui != null) {
	ui.installUI(this);
	}
	}
	}


	/**
	* Returns a string representation of this JPanel. This method
	* is intended to be used only for debugging purposes, and the
	* content and format of the returned string may vary between
	* implementations. The returned string may be empty but may not
	* be <code>null</code>.
	*
	* @return a string representation of this JPanel.
	*/
	protected String paramString() {
	return super.paramString();
	}

	/////////////////
	// Accessibility support
	////////////////

	/**
	* Gets the AccessibleContext associated with this JPanel.
	* For JPanels, the AccessibleContext takes the form of an
	* AccessibleJPanel.
	* A new AccessibleJPanel instance is created if necessary.
	*
	* @return an AccessibleJPanel that serves as the
	* AccessibleContext of this JPanel
	*/
	public AccessibleContext getAccessibleContext() {
	if (accessibleContext == null) {
	accessibleContext = new AccessibleJPanel();
	}
	return accessibleContext;
	}

	/**
	* This class implements accessibility support for the
	* <code>JPanel</code> class. It provides an implementation of the
	* Java Accessibility API appropriate to panel user-interface
	* elements.
	* <p>
	* <strong>Warning:</strong>
	* Serialized objects of this class will not be compatible with
	* future Swing releases. The current serialization support is
	* appropriate for short term storage or RMI between applications running
	* the same version of Swing. As of 1.4, support for long term storage
	* of all JavaBeans™
	* has been added to the <code>java.beans</code> package.
	* Please see {@link java.beans.XMLEncoder}.
	*/
	protected class AccessibleJPanel extends AccessibleJComponent {

	/**
	* Get the role of this object.
	*
	* @return an instance of AccessibleRole describing the role of the
	* object
	*/
	public AccessibleRole getAccessibleRole() {
	return AccessibleRole.PANEL;
	}
	}
	}

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