/*
 * @(#)ClassNotFoundException.java	1.20 04/02/19
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.lang;

/** Thrown when an application tries to load in a class through its string name using:
 * <ul>
 * <li>The <code>forName</code> method in class <code>Class</code>.
 * <li>The <code>findSystemClass</code> method in class <code>ClassLoader</code> .
 * <li>The <code>loadClass</code> method in class <code>ClassLoader</code>.
 * </ul>
 * <p>
 * but no definition for the class with the specified name could be found.
 * 
 * <p>
 * As of release 1.4, this exception has been retrofitted to conform to the general purpose exception-chaining mechanism. The
 * "optional exception that was raised while loading the class" that may be provided at construction time and accessed via the
 * {@link #getException()} method is now known as the <i>cause</i>, and may be accessed via the {@link Throwable#getCause()}
 * method, as well as the aforementioned "legacy method."
 * 
 * @author unascribed
 * @version 1.20, 02/19/04
 * @see java.lang.Class#forName(java.lang.String)
 * @see java.lang.ClassLoader#findSystemClass(java.lang.String)
 * @see java.lang.ClassLoader#loadClass(java.lang.String, boolean)
 * @since JDK1.0 */
public class ClassNotFoundException extends Exception {
	/** use serialVersionUID from JDK 1.1.X for interoperability */
	private static final long serialVersionUID = 9176873029745254542L;

	/** This field holds the exception ex if the ClassNotFoundException(String s, Throwable ex) constructor was used to instantiate
	 * the object
	 * @serial
	 * @since 1.2 */
	private Throwable ex;

	/** Constructs a <code>ClassNotFoundException</code> with no detail message. */
	public ClassNotFoundException () {
		super((Throwable)null); // Disallow initCause
	}

	/** Constructs a <code>ClassNotFoundException</code> with the specified detail message.
	 * 
	 * @param s the detail message. */
	public ClassNotFoundException (String s) {
		super(s, null); // Disallow initCause
	}

	/** Constructs a <code>ClassNotFoundException</code> with the specified detail message and optional exception that was raised
	 * while loading the class.
	 * 
	 * @param s the detail message
	 * @param ex the exception that was raised while loading the class
	 * @since 1.2 */
	public ClassNotFoundException (String s, Throwable ex) {
		super(s, null); // Disallow initCause
		this.ex = ex;
	}

	/** Returns the exception that was raised if an error occurred while attempting to load the class. Otherwise, returns
	 * <tt>null</tt>.
	 * 
	 * <p>
	 * This method predates the general-purpose exception chaining facility. The {@link Throwable#getCause()} method is now the
	 * preferred means of obtaining this information.
	 * 
	 * @return the <code>Exception</code> that was raised while loading a class
	 * @since 1.2 */
	public Throwable getException () {
		return ex;
	}

	/** Returns the cause of this exception (the exception that was raised if an error occurred while attempting to load the class;
	 * otherwise <tt>null</tt>).
	 * 
	 * @return the cause of this exception.
	 * @since 1.4 */
	public Throwable getCause () {
		return ex;
	}
}