/*

 * Copyright (c) 1997, 2006, 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 com.sun.jmx.snmp;

/**

 * Represents an SNMP null value.

 * <p><b>This API is a Sun Microsystems internal API  and is subject

 * to change without notice.</b></p>

 */

public class SnmpNull extends SnmpValue {

    private static final long serialVersionUID = 1783782515994279177L;

    // CONSTRUCTORS

    //-------------

    /**

     * Constructs a new <CODE>SnmpNull</CODE>.

     */

    public SnmpNull() {

        tag = NullTag ;

    }

    /**

     * Constructs a new <CODE>SnmpNull</CODE>.

     * <BR>For mibgen private use only.

     */

    public SnmpNull(String dummy) {

        this();

    }

    /**

     * Constructs a new <CODE>SnmpNull</CODE> from the specified tag value.

     * @param t The initialization value.

     */

    public SnmpNull(int t) {

        tag = t ;

    }

    // PUBLIC METHODS

    //---------------

    /**

     * Returns the tag value of this <CODE>SnmpNull</CODE>.

     * @return The value.

     */

    public int getTag() {

        return tag ;

    }

    /**

     * Converts the <CODE>NULL</CODE> value to its ASN.1 <CODE>String</CODE> form.

     * When the tag is not the universal one, it is preprended

     * to the <CODE>String</CODE> form.

     * @return The <CODE>String</CODE> representation of the value.

     */

    public String toString() {

        String result = "" ;

        if (tag != 5) {

            result += "[" + tag + "] " ;

        }

        result += "NULL" ;

        switch(tag) {

        case errNoSuchObjectTag :

            result += " (noSuchObject)" ;

            break ;

        case errNoSuchInstanceTag :

            result += " (noSuchInstance)" ;

            break ;

        case errEndOfMibViewTag :

            result += " (endOfMibView)" ;

            break ;

        }

        return result ;

    }

    /**

     * Converts the <CODE>NULL</CODE> value to its <CODE>SnmpOid</CODE> form.

     * Normally, a <CODE>NULL</CODE> value cannot be used as an index value,

     * this method triggers an exception.

     * @return The OID representation of the value.

     */

    public SnmpOid toOid() {

        throw new IllegalArgumentException() ;

    }

    /**

     * Performs a clone action. This provides a workaround for the

     * <CODE>SnmpValue</CODE> interface.

     * @return The SnmpValue clone.

     */

    final synchronized public SnmpValue duplicate() {

        return (SnmpValue) clone() ;

    }

    /**

     * Clones the <CODE>SnmpNull</CODE> object, making a copy of its data.

     * @return The object clone.

     */

    final synchronized public Object clone() {

        SnmpNull  newclone = null ;

        try {

            newclone = (SnmpNull) super.clone() ;

            newclone.tag = tag ;

        } catch (CloneNotSupportedException e) {

        }

        return newclone ;

    }

    /**

     * Returns a textual description of the type object.

     * @return ASN.1 textual description.

     */

    final public String getTypeName() {

        return name ;

    }

    /**

     * Checks if this <CODE>SnmpNull</CODE> object corresponds to a <CODE>noSuchObject</CODE> value.

     * @return <CODE>true</CODE> if the tag equals {@link com.sun.jmx.snmp.SnmpDataTypeEnums#errNoSuchObjectTag},

     * <CODE>false</CODE> otherwise.

     */

    public boolean isNoSuchObjectValue() {

        return (tag == SnmpDataTypeEnums.errNoSuchObjectTag);

    }

    /**

     * Checks if this <CODE>SnmpNull</CODE> object corresponds to a <CODE>noSuchInstance</CODE> value.

     * @return <CODE>true</CODE> if the tag equals {@link com.sun.jmx.snmp.SnmpDataTypeEnums#errNoSuchInstanceTag},

     * <CODE>false</CODE> otherwise.

     */

    public boolean isNoSuchInstanceValue() {

        return (tag == SnmpDataTypeEnums.errNoSuchInstanceTag);

    }

    /**

     * Checks if this <CODE>SnmpNull</CODE> object corresponds to an <CODE>endOfMibView</CODE> value.

     * @return <CODE>true</CODE> if the tag equals {@link com.sun.jmx.snmp.SnmpDataTypeEnums#errEndOfMibViewTag},

     * <CODE>false</CODE> otherwise.

     */

    public boolean isEndOfMibViewValue() {

        return (tag == SnmpDataTypeEnums.errEndOfMibViewTag);

    }

    // VARIABLES

    //----------

    /**

     * Name of the type.

     */

    final static String name = "Null" ;

    /**

     * This is the tag of the NULL value. By default, it is the universal tag value.

     */

    private int tag = 5 ;

}