/*
 * 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.lang;

import java.io.Serializable;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;

import org.apache.commons.lang.exception.CloneFailedException;
import org.apache.commons.lang.reflect.MethodUtils;

Operations on Object.
This class tries to handle null input gracefully.
An exception will generally not be thrown for a null input.
Each method documents its behaviour in more detail.
#ThreadSafe#
Author:
Apache Software Foundation, Nissim Karpenstein, Janek Bogucki, Daniel L. Rall, Gary Gregory, Mario Winterer, David J. M. Karlsen
Since:
1.0
Version:
$Id: ObjectUtils.java 1057434 2011-01-11 01:27:37Z niallp $/**
 * <p>Operations on <code>Object</code>.</p>
 * 
 * <p>This class tries to handle <code>null</code> input gracefully.
 * An exception will generally not be thrown for a <code>null</code> input.
 * Each method documents its behaviour in more detail.</p>
 *
 * <p>#ThreadSafe#</p>
 * @author Apache Software Foundation
 * @author <a href="mailto:nissim@nksystems.com">Nissim Karpenstein</a>
 * @author <a href="mailto:janekdb@yahoo.co.uk">Janek Bogucki</a>
 * @author Daniel L. Rall
 * @author Gary Gregory
 * @author Mario Winterer
 * @author <a href="mailto:david@davidkarlsen.com">David J. M. Karlsen</a>
 * @since 1.0
 * @version $Id: ObjectUtils.java 1057434 2011-01-11 01:27:37Z niallp $
 */
//@Immutable
public class ObjectUtils {

    
Singleton used as a null placeholder where
null has another meaning.
For example, in a HashMap the HashMap.get(Object) method returns null if the Map contains
null or if there is no matching key. The
Null placeholder can be used to distinguish between
these two cases.
Another example is Hashtable, where null
cannot be stored.
This instance is Serializable.
/**
     * <p>Singleton used as a <code>null</code> placeholder where
     * <code>null</code> has another meaning.</p>
     *
     * <p>For example, in a <code>HashMap</code> the
     * {@link java.util.HashMap#get(java.lang.Object)} method returns
     * <code>null</code> if the <code>Map</code> contains
     * <code>null</code> or if there is no matching key. The
     * <code>Null</code> placeholder can be used to distinguish between
     * these two cases.</p>
     *
     * <p>Another example is <code>Hashtable</code>, where <code>null</code>
     * cannot be stored.</p>
     *
     * <p>This instance is Serializable.</p>
     */
    public static final Null NULL = new Null();
    
    
ObjectUtils instances should NOT be constructed in
standard programming. Instead, the class should be used as
ObjectUtils.defaultIfNull("a","b");.
This constructor is public to permit tools that require a JavaBean instance
to operate.
/**
     * <p><code>ObjectUtils</code> instances should NOT be constructed in
     * standard programming. Instead, the class should be used as
     * <code>ObjectUtils.defaultIfNull("a","b");</code>.</p>
     *
     * <p>This constructor is public to permit tools that require a JavaBean instance
     * to operate.</p>
     */
    public ObjectUtils() {
        super();
    }

    // Defaulting
    //-----------------------------------------------------------------------
    
Returns a default value if the object passed is
null.
ObjectUtils.defaultIfNull(null, null)      = null
ObjectUtils.defaultIfNull(null, "")        = ""
ObjectUtils.defaultIfNull(null, "zz")      = "zz"
ObjectUtils.defaultIfNull("abc", *)        = "abc"
ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE

Params:
object –  the Object to test, may be null
defaultValue –  the default value to return, may be null
Returns:
object if it is not null, defaultValue otherwise/**
     * <p>Returns a default value if the object passed is
     * <code>null</code>.</p>
     * 
     * <pre>
     * ObjectUtils.defaultIfNull(null, null)      = null
     * ObjectUtils.defaultIfNull(null, "")        = ""
     * ObjectUtils.defaultIfNull(null, "zz")      = "zz"
     * ObjectUtils.defaultIfNull("abc", *)        = "abc"
     * ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE
     * </pre>
     *
     * @param object  the <code>Object</code> to test, may be <code>null</code>
     * @param defaultValue  the default value to return, may be <code>null</code>
     * @return <code>object</code> if it is not <code>null</code>, defaultValue otherwise
     */
    public static Object defaultIfNull(Object object, Object defaultValue) {
        return object != null ? object : defaultValue;
    }

    
Compares two objects for equality, where either one or both
objects may be null.
ObjectUtils.equals(null, null)                  = true
ObjectUtils.equals(null, "")                    = false
ObjectUtils.equals("", null)                    = false
ObjectUtils.equals("", "")                      = true
ObjectUtils.equals(Boolean.TRUE, null)          = false
ObjectUtils.equals(Boolean.TRUE, "true")        = false
ObjectUtils.equals(Boolean.TRUE, Boolean.TRUE)  = true
ObjectUtils.equals(Boolean.TRUE, Boolean.FALSE) = false

Params:
object1 –  the first object, may be null
object2 –  the second object, may be null
Returns:
true if the values of both objects are the same/**
     * <p>Compares two objects for equality, where either one or both
     * objects may be <code>null</code>.</p>
     *
     * <pre>
     * ObjectUtils.equals(null, null)                  = true
     * ObjectUtils.equals(null, "")                    = false
     * ObjectUtils.equals("", null)                    = false
     * ObjectUtils.equals("", "")                      = true
     * ObjectUtils.equals(Boolean.TRUE, null)          = false
     * ObjectUtils.equals(Boolean.TRUE, "true")        = false
     * ObjectUtils.equals(Boolean.TRUE, Boolean.TRUE)  = true
     * ObjectUtils.equals(Boolean.TRUE, Boolean.FALSE) = false
     * </pre>
     *
     * @param object1  the first object, may be <code>null</code>
     * @param object2  the second object, may be <code>null</code>
     * @return <code>true</code> if the values of both objects are the same
     */
    public static boolean equals(Object object1, Object object2) {
        if (object1 == object2) {
            return true;
        }
        if ((object1 == null) || (object2 == null)) {
            return false;
        }
        return object1.equals(object2);
    }

    
Compares two objects for inequality, where either one or both
objects may be null.
ObjectUtils.notEqual(null, null)                  = false
ObjectUtils.notEqual(null, "")                    = true
ObjectUtils.notEqual("", null)                    = true
ObjectUtils.notEqual("", "")                      = false
ObjectUtils.notEqual(Boolean.TRUE, null)          = true
ObjectUtils.notEqual(Boolean.TRUE, "true")        = true
ObjectUtils.notEqual(Boolean.TRUE, Boolean.TRUE)  = false
ObjectUtils.notEqual(Boolean.TRUE, Boolean.FALSE) = true

Params:
object1 –  the first object, may be null
object2 –  the second object, may be null
Returns:
false if the values of both objects are the same
Since:
2.6/**
     * <p>Compares two objects for inequality, where either one or both
     * objects may be <code>null</code>.</p>
     *
     * <pre>
     * ObjectUtils.notEqual(null, null)                  = false
     * ObjectUtils.notEqual(null, "")                    = true
     * ObjectUtils.notEqual("", null)                    = true
     * ObjectUtils.notEqual("", "")                      = false
     * ObjectUtils.notEqual(Boolean.TRUE, null)          = true
     * ObjectUtils.notEqual(Boolean.TRUE, "true")        = true
     * ObjectUtils.notEqual(Boolean.TRUE, Boolean.TRUE)  = false
     * ObjectUtils.notEqual(Boolean.TRUE, Boolean.FALSE) = true
     * </pre>
     *
     * @param object1  the first object, may be <code>null</code>
     * @param object2  the second object, may be <code>null</code>
     * @return <code>false</code> if the values of both objects are the same
     * @since 2.6
     */
    public static boolean notEqual(Object object1, Object object2) {
        return ObjectUtils.equals(object1, object2) == false;
    }

    
Gets the hash code of an object returning zero when the
object is null.
ObjectUtils.hashCode(null)   = 0
ObjectUtils.hashCode(obj)    = obj.hashCode()

Params:
obj –  the object to obtain the hash code of, may be null
Returns:
the hash code of the object, or zero if null
Since:
2.1/**
     * <p>Gets the hash code of an object returning zero when the
     * object is <code>null</code>.</p>
     *
     * <pre>
     * ObjectUtils.hashCode(null)   = 0
     * ObjectUtils.hashCode(obj)    = obj.hashCode()
     * </pre>
     *
     * @param obj  the object to obtain the hash code of, may be <code>null</code>
     * @return the hash code of the object, or zero if null
     * @since 2.1
     */
    public static int hashCode(Object obj) {
        return (obj == null) ? 0 : obj.hashCode();
    }

    // Identity ToString
    //-----------------------------------------------------------------------
    
Gets the toString that would be produced by Object
if a class did not override toString itself. null
will return null.
ObjectUtils.identityToString(null)         = null
ObjectUtils.identityToString("")           = "java.lang.String@1e23"
ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa"

Params:
object –  the object to create a toString for, may be
 null
Returns:
the default toString text, or null if
 null passed in/**
     * <p>Gets the toString that would be produced by <code>Object</code>
     * if a class did not override toString itself. <code>null</code>
     * will return <code>null</code>.</p>
     *
     * <pre>
     * ObjectUtils.identityToString(null)         = null
     * ObjectUtils.identityToString("")           = "java.lang.String@1e23"
     * ObjectUtils.identityToString(Boolean.TRUE) = "java.lang.Boolean@7fa"
     * </pre>
     *
     * @param object  the object to create a toString for, may be
     *  <code>null</code>
     * @return the default toString text, or <code>null</code> if
     *  <code>null</code> passed in
     */
    public static String identityToString(Object object) {
        if (object == null) {
            return null;
        }
        StringBuffer buffer = new StringBuffer();
        identityToString(buffer, object);
        return buffer.toString();
    }

    
Appends the toString that would be produced by Object
if a class did not override toString itself. null
will throw a NullPointerException for either of the two parameters. 
ObjectUtils.identityToString(buf, "")            = buf.append("java.lang.String@1e23"
ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa"
ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa")

Params:
buffer –  the buffer to append to
object –  the object to create a toString for
Since:
2.4/**
     * <p>Appends the toString that would be produced by <code>Object</code>
     * if a class did not override toString itself. <code>null</code>
     * will throw a NullPointerException for either of the two parameters. </p>
     *
     * <pre>
     * ObjectUtils.identityToString(buf, "")            = buf.append("java.lang.String@1e23"
     * ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa"
     * ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa")
     * </pre>
     *
     * @param buffer  the buffer to append to
     * @param object  the object to create a toString for
     * @since 2.4
     */
    public static void identityToString(StringBuffer buffer, Object object) {
        if (object == null) {
            throw new NullPointerException("Cannot get the toString of a null identity");
        }
        buffer.append(object.getClass().getName())
              .append('@')
              .append(Integer.toHexString(System.identityHashCode(object)));
    }

    
Appends the toString that would be produced by Object
if a class did not override toString itself. null
will return null.
ObjectUtils.appendIdentityToString(*, null)            = null
ObjectUtils.appendIdentityToString(null, "")           = "java.lang.String@1e23"
ObjectUtils.appendIdentityToString(null, Boolean.TRUE) = "java.lang.Boolean@7fa"
ObjectUtils.appendIdentityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa")

Params:
buffer –  the buffer to append to, may be null
object –  the object to create a toString for, may be null
Returns:
the default toString text, or null if
 null passed in
Since:
2.0
Deprecated:
The design of this method is bad - see LANG-360. Instead, use identityToString(StringBuffer, Object)./**
     * <p>Appends the toString that would be produced by <code>Object</code>
     * if a class did not override toString itself. <code>null</code>
     * will return <code>null</code>.</p>
     *
     * <pre>
     * ObjectUtils.appendIdentityToString(*, null)            = null
     * ObjectUtils.appendIdentityToString(null, "")           = "java.lang.String@1e23"
     * ObjectUtils.appendIdentityToString(null, Boolean.TRUE) = "java.lang.Boolean@7fa"
     * ObjectUtils.appendIdentityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa")
     * </pre>
     *
     * @param buffer  the buffer to append to, may be <code>null</code>
     * @param object  the object to create a toString for, may be <code>null</code>
     * @return the default toString text, or <code>null</code> if
     *  <code>null</code> passed in
     * @since 2.0
     * @deprecated The design of this method is bad - see LANG-360. Instead, use identityToString(StringBuffer, Object).
     */
    public static StringBuffer appendIdentityToString(StringBuffer buffer, Object object) {
        if (object == null) {
            return null;
        }
        if (buffer == null) {
            buffer = new StringBuffer();
        }
        return buffer
            .append(object.getClass().getName())
            .append('@')
            .append(Integer.toHexString(System.identityHashCode(object)));
    }

    // ToString
    //-----------------------------------------------------------------------
    
Gets the toString of an Object returning
an empty string ("") if null input.
ObjectUtils.toString(null)         = ""
ObjectUtils.toString("")           = ""
ObjectUtils.toString("bat")        = "bat"
ObjectUtils.toString(Boolean.TRUE) = "true"

Params:
obj –  the Object to toString, may be null
See Also:
defaultString.defaultString(String)
String.valueOf(Object)
Returns:
the passed in Object's toString, or nullStr if null input
Since:
2.0/**
     * <p>Gets the <code>toString</code> of an <code>Object</code> returning
     * an empty string ("") if <code>null</code> input.</p>
     * 
     * <pre>
     * ObjectUtils.toString(null)         = ""
     * ObjectUtils.toString("")           = ""
     * ObjectUtils.toString("bat")        = "bat"
     * ObjectUtils.toString(Boolean.TRUE) = "true"
     * </pre>
     * 
     * @see StringUtils#defaultString(String)
     * @see String#valueOf(Object)
     * @param obj  the Object to <code>toString</code>, may be null
     * @return the passed in Object's toString, or nullStr if <code>null</code> input
     * @since 2.0
     */
    public static String toString(Object obj) {
        return obj == null ? "" : obj.toString();
    }

    
Gets the toString of an Object returning
a specified text if null input.
ObjectUtils.toString(null, null)           = null
ObjectUtils.toString(null, "null")         = "null"
ObjectUtils.toString("", "null")           = ""
ObjectUtils.toString("bat", "null")        = "bat"
ObjectUtils.toString(Boolean.TRUE, "null") = "true"

Params:
obj –  the Object to toString, may be null
nullStr –  the String to return if null input, may be null
See Also:
defaultString.defaultString(String, String)
String.valueOf(Object)
Returns:
the passed in Object's toString, or nullStr if null input
Since:
2.0/**
     * <p>Gets the <code>toString</code> of an <code>Object</code> returning
     * a specified text if <code>null</code> input.</p>
     * 
     * <pre>
     * ObjectUtils.toString(null, null)           = null
     * ObjectUtils.toString(null, "null")         = "null"
     * ObjectUtils.toString("", "null")           = ""
     * ObjectUtils.toString("bat", "null")        = "bat"
     * ObjectUtils.toString(Boolean.TRUE, "null") = "true"
     * </pre>
     * 
     * @see StringUtils#defaultString(String,String)
     * @see String#valueOf(Object)
     * @param obj  the Object to <code>toString</code>, may be null
     * @param nullStr  the String to return if <code>null</code> input, may be null
     * @return the passed in Object's toString, or nullStr if <code>null</code> input
     * @since 2.0
     */
    public static String toString(Object obj, String nullStr) {
        return obj == null ? nullStr : obj.toString();
    }

    // Min/Max
    //-----------------------------------------------------------------------
    
Null safe comparison of Comparables.
Params:
c1 –  the first comparable, may be null
c2 –  the second comparable, may be null
Returns:

 

  
If both objects are non-null and unequal, the lesser object.
  
If both objects are non-null and equal, c1.
  
If one of the comparables is null, the non-null object.
  
If both the comparables are null, null is returned.
 /**
     * Null safe comparison of Comparables.
     * 
     * @param c1  the first comparable, may be null
     * @param c2  the second comparable, may be null
     * @return

     *  <ul>
     *   <li>If both objects are non-null and unequal, the lesser object.
     *   <li>If both objects are non-null and equal, c1.
     *   <li>If one of the comparables is null, the non-null object.
     *   <li>If both the comparables are null, null is returned.
     *  </ul>
     */
    public static Object min(Comparable c1, Comparable c2) {
        return (compare(c1, c2, true) <= 0 ? c1 : c2);
    }

    
Null safe comparison of Comparables.
Params:
c1 –  the first comparable, may be null
c2 –  the second comparable, may be null
Returns:

 

  
If both objects are non-null and unequal, the greater object.
  
If both objects are non-null and equal, c1.
  
If one of the comparables is null, the non-null object.
  
If both the comparables are null, null is returned.
 /**
     * Null safe comparison of Comparables.
     * 
     * @param c1  the first comparable, may be null
     * @param c2  the second comparable, may be null
     * @return

     *  <ul>
     *   <li>If both objects are non-null and unequal, the greater object.
     *   <li>If both objects are non-null and equal, c1.
     *   <li>If one of the comparables is null, the non-null object.
     *   <li>If both the comparables are null, null is returned.
     *  </ul>
     */
    public static Object max(Comparable c1, Comparable c2) {
        return (compare(c1, c2, false) >= 0 ? c1 : c2);
    }

    
Null safe comparison of Comparables. null is assumed to be less than a non-null value. 
Params:
c1 –  the first comparable, may be null
c2 –  the second comparable, may be null
Returns:
a negative value if c1 < c2, zero if c1 = c2
and a positive value if c1 > c2
Since:
2.6/**
     * Null safe comparison of Comparables.
     * {@code null} is assumed to be less than a non-{@code null} value.
     * 
     * @param c1  the first comparable, may be null
     * @param c2  the second comparable, may be null
     * @return a negative value if c1 < c2, zero if c1 = c2
     * and a positive value if c1 > c2
     * @since 2.6
     */
    public static int compare(Comparable c1, Comparable c2) {
        return compare(c1, c2, false);
    }

    
Null safe comparison of Comparables.
Params:
c1 –  the first comparable, may be null
c2 –  the second comparable, may be null
nullGreater – if true null is considered greater
than a Non-null value or if false null is
considered less than a Non-null value
See Also:
Comparator.compare(Object, Object)
Returns:
a negative value if c1 < c2, zero if c1 = c2
and a positive value if c1 > c2
Since:
2.6/**
     * Null safe comparison of Comparables.
     * 
     * @param c1  the first comparable, may be null
     * @param c2  the second comparable, may be null
     * @param nullGreater if true <code>null</code> is considered greater
     * than a Non-<code>null</code> value or if false <code>null</code> is
     * considered less than a Non-<code>null</code> value
     * @return a negative value if c1 < c2, zero if c1 = c2
     * and a positive value if c1 > c2
     * @see java.util.Comparator#compare(Object, Object)
     * @since 2.6
     */
    public static int compare(Comparable c1, Comparable c2, boolean nullGreater) {
        if (c1 == c2) {
            return 0;
        } else if (c1 == null) {
            return (nullGreater ? 1 : -1);
        } else if (c2 == null) {
            return (nullGreater ? -1 : 1);
        }
        return c1.compareTo(c2);
    }
    
    
Clone an object.
Params:
o – the object to clone
Throws:
CloneFailedException – if the object is cloneable and the clone operation fails
Returns:
the clone if the object implements Cloneable otherwise null
Since:
2.6/**
     * Clone an object.
     * 
     * @param o the object to clone
     * @return the clone if the object implements {@link Cloneable} otherwise <code>null</code>
     * @throws CloneFailedException if the object is cloneable and the clone operation fails
     * @since 2.6
     */
    public static Object clone(final Object o) {
        if (o instanceof Cloneable) {
            final Object result;
            if (o.getClass().isArray()) {
                final Class componentType = o.getClass().getComponentType();
                if (!componentType.isPrimitive()) {
                    result = ((Object[])o).clone();
                } else {
                    int length = Array.getLength(o);
                    result = Array.newInstance(componentType, length);
                    while (length-- > 0) {
                        Array.set(result, length, Array.get(o, length));
                    }
                }
            } else {
                try {
                    result = MethodUtils.invokeMethod(o, "clone", null);
                } catch (final NoSuchMethodException e) {
                    throw new CloneFailedException("Cloneable type "
                        + o.getClass().getName()
                        + " has no clone method", e);
                } catch (final IllegalAccessException e) {
                    throw new CloneFailedException("Cannot clone Cloneable type "
                        + o.getClass().getName(), e);
                } catch (final InvocationTargetException e) {
                    throw new CloneFailedException("Exception cloning Cloneable type "
                        + o.getClass().getName(), e.getTargetException());
                }
            }
            return result;
        }

        return null;
    }

    
Clone an object if possible. This method is similar to clone(Object), but will return the provided instance as the return value instead of null if the instance
is not cloneable. This is more convenient if the caller uses different
implementations (e.g. of a service) and some of the implementations do not allow concurrent
processing or have state. In such cases the implementation can simply provide a proper
clone implementation and the caller's code does not have to change.
Params:
o – the object to clone
Throws:
CloneFailedException – if the object is cloneable and the clone operation fails
Returns:
the clone if the object implements Cloneable otherwise the object itself
Since:
2.6/**
     * Clone an object if possible. This method is similar to {@link #clone(Object)}, but will
     * return the provided instance as the return value instead of <code>null</code> if the instance
     * is not cloneable. This is more convenient if the caller uses different
     * implementations (e.g. of a service) and some of the implementations do not allow concurrent
     * processing or have state. In such cases the implementation can simply provide a proper
     * clone implementation and the caller's code does not have to change.
     * 
     * @param o the object to clone
     * @return the clone if the object implements {@link Cloneable} otherwise the object itself
     * @throws CloneFailedException if the object is cloneable and the clone operation fails
     * @since 2.6
     */
    public static Object cloneIfPossible(final Object o) {
        final Object clone = clone(o);
        return clone == null ? o : clone;
    }

    // Null
    //-----------------------------------------------------------------------
    
Class used as a null placeholder where null
has another meaning.
For example, in a HashMap the HashMap.get(Object) method returns null if the Map contains
null or if there is no matching key. The
Null placeholder can be used to distinguish between
these two cases.
Another example is Hashtable, where null
cannot be stored.
/**
     * <p>Class used as a null placeholder where <code>null</code>
     * has another meaning.</p>
     *
     * <p>For example, in a <code>HashMap</code> the
     * {@link java.util.HashMap#get(java.lang.Object)} method returns
     * <code>null</code> if the <code>Map</code> contains
     * <code>null</code> or if there is no matching key. The
     * <code>Null</code> placeholder can be used to distinguish between
     * these two cases.</p>
     *
     * <p>Another example is <code>Hashtable</code>, where <code>null</code>
     * cannot be stored.</p>
     */
    public static class Null implements Serializable {
        
Required for serialization support. Declare serialization compatibility with Commons Lang 1.0
See Also:
Serializable/**
         * Required for serialization support. Declare serialization compatibility with Commons Lang 1.0
         * 
         * @see java.io.Serializable
         */
        private static final long serialVersionUID = 7092611880189329093L;
        
        
Restricted constructor - singleton.
/**
         * Restricted constructor - singleton.
         */
        Null() {
            super();
        }
        
        
Ensure singleton.
Returns:
the singleton value/**
         * <p>Ensure singleton.</p>
         * 
         * @return the singleton value
         */
        private Object readResolve() {
            return ObjectUtils.NULL;
        }
    }

}