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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
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/**
 * 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.builder;

import java.lang.reflect.Type;

import org.apache.commons.lang3.ObjectUtils;
import org.apache.commons.lang3.reflect.TypeUtils;
import org.apache.commons.lang3.tuple.Pair;

 A Diff contains the differences between two Diffable class fields. 
 Typically, Diffs are retrieved by using a DiffBuilder to produce a DiffResult, containing the differences between two objects. 
Type parameters:
<T> –  The type of object contained within this Diff. Differences between primitive objects are stored as their Object wrapper equivalent.
Since:
3.3/**
 * <p>
 * A {@code Diff} contains the differences between two {@link Diffable} class
 * fields.
 * </p>
 *
 * <p>
 * Typically, {@code Diff}s are retrieved by using a {@link DiffBuilder} to
 * produce a {@link DiffResult}, containing the differences between two objects.
 * </p>
 *
 *
 * @param <T>
 *            The type of object contained within this {@code Diff}. Differences
 *            between primitive objects are stored as their Object wrapper
 *            equivalent.
 * @since 3.3
 */
public abstract class Diff<T> extends Pair<T, T> {

    private static final long serialVersionUID = 1L;

    private final Type type;
    private final String fieldName;

    
 Constructs a new Diff for the given field name. 
Params:
fieldName – 
           the name of the field/**
     * <p>
     * Constructs a new {@code Diff} for the given field name.
     * </p>
     *
     * @param fieldName
     *            the name of the field
     */
    protected Diff(final String fieldName) {
        this.type = ObjectUtils.defaultIfNull(
                TypeUtils.getTypeArguments(getClass(), Diff.class).get(
                        Diff.class.getTypeParameters()[0]), Object.class);
        this.fieldName = fieldName;
    }

    

Returns the type of the field.

Returns:
the field type/**
     * <p>
     * Returns the type of the field.
     * </p>
     *
     * @return the field type
     */
    public final Type getType() {
        return type;
    }

    

Returns the name of the field.

Returns:
the field name/**
     * <p>
     * Returns the name of the field.
     * </p>
     *
     * @return the field name
     */
    public final String getFieldName() {
        return fieldName;
    }

    
 Returns a String representation of the Diff, with the following format:
[fieldname: left-value, right-value]

Returns:
the string representation/**
     * <p>
     * Returns a {@code String} representation of the {@code Diff}, with the
     * following format:</p>
     *
     * <pre>
     * [fieldname: left-value, right-value]
     * </pre>
     *
     *
     * @return the string representation
     */
    @Override
    public final String toString() {
        return String.format("[%s: %s, %s]", fieldName, getLeft(), getRight());
    }

    
 Throws UnsupportedOperationException. 
Params:
value – 
           ignored
Returns:
nothing/**
     * <p>
     * Throws {@code UnsupportedOperationException}.
     * </p>
     *
     * @param value
     *            ignored
     * @return nothing
     */
    @Override
    public final T setValue(final T value) {
        throw new UnsupportedOperationException("Cannot alter Diff object.");
    }
}