/*_############################################################################ _## _## SNMP4J - Null.java _## _## Copyright 2003-2006 Frank Fock and Jochen Katz (SNMP4J.org) _## _## Licensed 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.snmp4j.smi; import java.io.*; import org.snmp4j.asn1.BER; import org.snmp4j.asn1.BERInputStream; import org.snmp4j.asn1.BER.MutableByte; /** * The Null class represents SMI Null and the derived * SMIv2 exception syntaxes. * * @author Frank Fock * @version 1.7 */ public class Null extends Variable { private static final long serialVersionUID = 6907924131098190092L; private int syntax = SMIConstants.SYNTAX_NULL; public static final Null noSuchObject = new Null(SMIConstants.EXCEPTION_NO_SUCH_OBJECT); public static final Null noSuchInstance = new Null(SMIConstants.EXCEPTION_NO_SUCH_INSTANCE); public static final Null endOfMibView = new Null(SMIConstants.EXCEPTION_END_OF_MIB_VIEW); public static final Null instance = new Null(SMIConstants.SYNTAX_NULL); public Null() { } public Null(int exceptionSyntax) { setSyntax(exceptionSyntax); } public void decodeBER(BERInputStream inputStream) throws java.io.IOException { MutableByte type = new BER.MutableByte(); BER.decodeNull(inputStream, type); this.syntax = type.getValue() & 0xFF; } public int getSyntax() { return syntax; } public int hashCode() { return getSyntax(); } public int getBERLength() { return 2; } public boolean equals(Object o) { if (o instanceof Null) { return (((Null) o).getSyntax() == getSyntax()); } return false; } public int compareTo(Object o) { return (getSyntax() - ((Null)o).getSyntax()); } public String toString() { switch (getSyntax()) { case SMIConstants.EXCEPTION_NO_SUCH_OBJECT: return "noSuchObject"; case SMIConstants.EXCEPTION_NO_SUCH_INSTANCE: return "noSuchInstance"; case SMIConstants.EXCEPTION_END_OF_MIB_VIEW: return "endOfMibView"; } return "Null"; } public void encodeBER(OutputStream outputStream) throws java.io.IOException { BER.encodeHeader(outputStream, (byte)getSyntax(), 0); } public void setSyntax(int syntax) { if ((syntax != SMIConstants.SYNTAX_NULL) && (!isExceptionSyntax(syntax))) { throw new IllegalArgumentException("Syntax " + syntax + " is incompatible with Null type"); } this.syntax = syntax; } public Object clone() { return new Null(); } public static boolean isExceptionSyntax(int syntax) { switch (syntax) { case SMIConstants.EXCEPTION_NO_SUCH_OBJECT: case SMIConstants.EXCEPTION_NO_SUCH_INSTANCE: case SMIConstants.EXCEPTION_END_OF_MIB_VIEW: return true; } return false; } /** * Returns the syntax of this Null variable. * @return * {@link SMIConstants#SYNTAX_NULL} or one of the exception syntaxes * {@link SMIConstants#EXCEPTION_NO_SUCH_OBJECT}, * {@link SMIConstants#EXCEPTION_NO_SUCH_INSTANCE}, or * {@link SMIConstants#EXCEPTION_END_OF_MIB_VIEW} * @since 1.7 */ public final int toInt() { return getSyntax(); } /** * Returns the syntax of this Null variable. * @return * {@link SMIConstants#SYNTAX_NULL} or one of the exception syntaxes * {@link SMIConstants#EXCEPTION_NO_SUCH_OBJECT}, * {@link SMIConstants#EXCEPTION_NO_SUCH_INSTANCE}, or * {@link SMIConstants#EXCEPTION_END_OF_MIB_VIEW} * @since 1.7 */ public final long toLong() { return getSyntax(); } public OID toSubIndex(boolean impliedLength) { throw new UnsupportedOperationException(); } public void fromSubIndex(OID subIndex, boolean impliedLength) { throw new UnsupportedOperationException(); } @Override public Object getValue() { return null; } }
