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Java example source code file (DefaultExceptionContext.java)

This example Java source code file (DefaultExceptionContext.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, context:\n, defaultexceptioncontext, exception, immutablepair, iterator, list, object, override, pair, serializable, set, string, stringbuilder, util

The DefaultExceptionContext.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3.exception;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.tuple.ImmutablePair;
import org.apache.commons.lang3.tuple.Pair;

/**
 * Default implementation of the context storing the label-value pairs for contexted exceptions.
 * <p>
 * This implementation is serializable, however this is dependent on the values that
 * are added also being serializable.
 * </p>
 * 
 * @see ContextedException
 * @see ContextedRuntimeException
 * @since 3.0
 */
public class DefaultExceptionContext implements ExceptionContext, Serializable {

    /** The serialization version. */
    private static final long serialVersionUID = 20110706L;

    /** The list storing the label-data pairs. */
    private final List<Pair contextValues = new ArrayList>();

    /**
     * {@inheritDoc}
     */
    @Override
    public DefaultExceptionContext addContextValue(final String label, final Object value) {
        contextValues.add(new ImmutablePair<String, Object>(label, value));
        return this;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public DefaultExceptionContext setContextValue(final String label, final Object value) {
        for (final Iterator<Pair iter = contextValues.iterator(); iter.hasNext();) {
            final Pair<String, Object> p = iter.next();
            if (StringUtils.equals(label, p.getKey())) {
                iter.remove();
            }
        }
        addContextValue(label, value);
        return this;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Object> getContextValues(final String label) {
        final List<Object> values = new ArrayList();
        for (final Pair<String, Object> pair : contextValues) {
            if (StringUtils.equals(label, pair.getKey())) {
                values.add(pair.getValue());
            }
        }
        return values;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Object getFirstContextValue(final String label) {
        for (final Pair<String, Object> pair : contextValues) {
            if (StringUtils.equals(label, pair.getKey())) {
                return pair.getValue();
            }
        }
        return null;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Set<String> getContextLabels() {
        final Set<String> labels = new HashSet();
        for (final Pair<String, Object> pair : contextValues) {
            labels.add(pair.getKey());
        }
        return labels;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List<Pair getContextEntries() {
        return contextValues;
    }

    /**
     * Builds the message containing the contextual information.
     * 
     * @param baseMessage  the base exception message <b>without context information appended
     * @return the exception message <b>with context information appended, never null
     */
    @Override
    public String getFormattedExceptionMessage(final String baseMessage){
        final StringBuilder buffer = new StringBuilder(256);
        if (baseMessage != null) {
            buffer.append(baseMessage);
        }
        
        if (contextValues.size() > 0) {
            if (buffer.length() > 0) {
                buffer.append('\n');
            }
            buffer.append("Exception Context:\n");
            
            int i = 0;
            for (final Pair<String, Object> pair : contextValues) {
                buffer.append("\t[");
                buffer.append(++i);
                buffer.append(':');
                buffer.append(pair.getKey());
                buffer.append("=");
                final Object value = pair.getValue();
                if (value == null) {
                    buffer.append("null");
                } else {
                    String valueStr;
                    try {
                        valueStr = value.toString();
                    } catch (final Exception e) {
                        valueStr = "Exception thrown on toString(): " + ExceptionUtils.getStackTrace(e);
                    }
                    buffer.append(valueStr);
                }
                buffer.append("]\n");
            }
            buffer.append("---------------------------------");
        }
        return buffer.toString();
    }

}




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