Java tutorial
/* * Copyright (c) 2003, 2017, 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.xml.xpath; import java.io.PrintWriter; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.ObjectStreamField; import java.io.InvalidClassException; /** * {@code XPathException} represents a generic XPath exception. * * @author Norman Walsh * @author Jeff Suttor * @since 1.5 */ public class XPathException extends Exception { private static final ObjectStreamField[] serialPersistentFields = { new ObjectStreamField("cause", Throwable.class) }; /** * Stream Unique Identifier. */ private static final long serialVersionUID = -1837080260374986980L; /** * Constructs a new {@code XPathException} * with the specified detail {@code message}. * * <p>The {@code cause} is not initialized. * * <p>If {@code message} is {@code null}, * then a {@code NullPointerException} is thrown. * * @param message The detail message. * * @throws NullPointerException When {@code message} is * {@code null}. */ public XPathException(String message) { super(message); if (message == null) { throw new NullPointerException("message can't be null"); } } /** * Constructs a new {@code XPathException} * with the specified {@code cause}. * * <p>If {@code cause} is {@code null}, * then a {@code NullPointerException} is thrown. * * @param cause The cause. * * @throws NullPointerException if {@code cause} is {@code null}. */ public XPathException(Throwable cause) { super(cause); if (cause == null) { throw new NullPointerException("cause can't be null"); } } /** * Get the cause of this XPathException. * * @return Cause of this XPathException. */ public Throwable getCause() { return super.getCause(); } /** * Writes "cause" field to the stream. * The cause is got from the parent class. * * @param out stream used for serialization. * @throws IOException thrown by {@code ObjectOutputStream} * */ private void writeObject(ObjectOutputStream out) throws IOException { ObjectOutputStream.PutField fields = out.putFields(); fields.put("cause", super.getCause()); out.writeFields(); } /** * Reads the "cause" field from the stream. * And initializes the "cause" if it wasn't * done before. * * @param in stream used for deserialization * @throws IOException thrown by {@code ObjectInputStream} * @throws ClassNotFoundException thrown by {@code ObjectInputStream} */ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { ObjectInputStream.GetField fields = in.readFields(); Throwable scause = (Throwable) fields.get("cause", null); if (super.getCause() == null && scause != null) { try { super.initCause(scause); } catch (IllegalStateException e) { throw new InvalidClassException("Inconsistent state: two causes"); } } } /** * Print stack trace to specified {@code PrintStream}. * * @param s Print stack trace to this {@code PrintStream}. */ public void printStackTrace(java.io.PrintStream s) { if (getCause() != null) { getCause().printStackTrace(s); s.println("--------------- linked to ------------------"); } super.printStackTrace(s); } /** * Print stack trace to {@code System.err}. */ public void printStackTrace() { printStackTrace(System.err); } /** * Print stack trace to specified {@code PrintWriter}. * * @param s Print stack trace to this {@code PrintWriter}. */ public void printStackTrace(PrintWriter s) { if (getCause() != null) { getCause().printStackTrace(s); s.println("--------------- linked to ------------------"); } super.printStackTrace(s); } }