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 * Copyright (c) 2000, 2019, 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
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package javax.xml.transform;


The listener interface used by a TransformerFactory or Transformer to notify callers of error messages that occur during a transformation process. An ErrorListener receives three levels of messages: warnings, errors and fatal errors as classified by their severity. Each of them is handled as described in their respective method. 
 An ErrorListener instance can be registered to a TransformerFactory or Transformer through the TransformerFactory.setErrorListener(ErrorListener) or Transformer.setErrorListener(ErrorListener) method to receive errors and warnings reported by the TransformerFactory or Transformer. 
 When a listener is registered, the TransformerFactory or Transformer must use this interface to pass on all warnings and errors to the listener and let the application decide how to handle them. Note that the TransformerFactory or Transformer is not required to continue with the transformation after a call to fatalError(TransformerException exception). 
 If an application does not provide a listener, the TransformerFactory or Transformer shall create one on its own. The default ErrorListener may take no action for warnings and recoverable errors, and allow the transformation to continue. However, the TransformerFactory or Transformer may still throw TransformerException when it decides it can not continue processing. 
API Note:It is recommended that applications register and use their own ErrorListener to override the default behavior in order to ensure proper handling of warnings and errors.
Since:1.4
/**
 * The listener interface used by a {@link TransformerFactory} or {@link Transformer}
 * to notify callers of error messages that occur during a transformation process.
 * An ErrorListener receives three levels of messages: warnings, errors and fatal
 * errors as classified by their severity. Each of them is handled as described
 * in their respective method.
 *
 * <p>
 * An ErrorListener instance can be registered to a {@link TransformerFactory}
 * or {@link Transformer} through
 * the {@link TransformerFactory#setErrorListener(ErrorListener)}
 * or {@link Transformer#setErrorListener(ErrorListener)}
 * method to receive errors and warnings reported by the TransformerFactory
 * or Transformer.
 *
 * <p>
 * When a listener is registered, the {@link TransformerFactory} or {@link Transformer}
 * must use this interface to pass on all warnings and errors to the listener
 * and let the application decide how to handle them.
 * Note that the {@code TransformerFactory} or {@code Transformer} is not
 * required to continue with the transformation after a call to
 * {@link #fatalError(TransformerException exception)}.
 *
 * <p>
 * If an application does not provide a listener, the {@link TransformerFactory}
 * or {@link Transformer} shall create one on its own. The default {@code ErrorListener}
 * may take no action for warnings and recoverable errors, and allow the
 * transformation to continue.
 * However, the {@code TransformerFactory} or {@code Transformer} may still throw
 * {@code TransformerException} when it decides it can not continue processing.
 *
 * @apiNote It is recommended that applications register and use their own
 * {@code ErrorListener} to override the default behavior in order to ensure
 * proper handling of warnings and errors.
 *
 * @since 1.4
 */
public interface ErrorListener {

    
Receive notification of a warning.

Transformer can use this method to report conditions that are not errors or fatal errors. The default behaviour is to take no action.


After invoking this method, the Transformer must continue with
the transformation. It should still be possible for the
application to process the document through to the end.


Params:
  • exception – The warning information encapsulated in a
                 transformer exception.
Throws:
See Also:
/**
     * Receive notification of a warning.
     *
     * <p>{@link javax.xml.transform.Transformer} can use this method to report
     * conditions that are not errors or fatal errors.  The default behaviour
     * is to take no action.</p>
     *
     * <p>After invoking this method, the Transformer must continue with
     * the transformation. It should still be possible for the
     * application to process the document through to the end.</p>
     *
     * @param exception The warning information encapsulated in a
     *                  transformer exception.
     *
     * @throws javax.xml.transform.TransformerException if the application
     * chooses to discontinue the transformation.
     *
     * @see javax.xml.transform.TransformerException
     */
    public abstract void warning(TransformerException exception)
        throws TransformerException;

    
Receive notification of a recoverable error.

The transformer must continue to try and provide normal transformation
after invoking this method.  It should still be possible for the
application to process the document through to the end if no other errors
are encountered.


Params:
  • exception – The error information encapsulated in a
                 transformer exception.
Throws:
See Also:
/**
     * Receive notification of a recoverable error.
     *
     * <p>The transformer must continue to try and provide normal transformation
     * after invoking this method.  It should still be possible for the
     * application to process the document through to the end if no other errors
     * are encountered.</p>
     *
     * @param exception The error information encapsulated in a
     *                  transformer exception.
     *
     * @throws javax.xml.transform.TransformerException if the application
     * chooses to discontinue the transformation.
     *
     * @see javax.xml.transform.TransformerException
     */
    public abstract void error(TransformerException exception)
        throws TransformerException;

    
Receive notification of a non-recoverable error.


The processor may choose to continue, but will not normally
proceed to a successful completion.


The method should throw an exception if it is unable to
process the error, or if it wishes execution to terminate
immediately. The processor will not necessarily honor this
request.


Params:
  • exception – The error information encapsulated in a
   TransformerException.
Throws:
See Also:
/**
     * <p>Receive notification of a non-recoverable error.</p>
     *
     * <p>The processor may choose to continue, but will not normally
     * proceed to a successful completion.</p>
     *
     * <p>The method should throw an exception if it is unable to
     * process the error, or if it wishes execution to terminate
     * immediately. The processor will not necessarily honor this
     * request.</p>
     *
     * @param exception The error information encapsulated in a
     *    <code>TransformerException</code>.
     *
     * @throws javax.xml.transform.TransformerException if the application
     * chooses to discontinue the transformation.
     *
     * @see javax.xml.transform.TransformerException
     */
    public abstract void fatalError(TransformerException exception)
        throws TransformerException;
}