Module org.snmp4j
Package org.snmp4j.smi

Interface Variable

All Superinterfaces:
BERSerializable, Cloneable, Comparable<Variable>
All Known Implementing Classes:
AbstractVariable, BitString, Counter32, Counter64, DtlsAddress, Gauge32, GenericAddress, Integer32, IpAddress, Null, OctetString, OID, Opaque, SecretOctetString, SMIAddress, TcpAddress, TimeTicks, TlsAddress, TransportIpAddress, TsmSecurityParameters, UdpAddress, UnsignedInteger32, VariantVariable
public interface Variable extends Cloneable, Comparable<Variable>, BERSerializable
The Variable interface defines common attributes of all SNMP variables.

Before version 1.8, Variable has been an abstract class which has been renamed to AbstractVariable.

Since:
1.8
Version:
1.8
Author:
Frank Fock

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final long
    serialVersionUID
    This definition of a serialVersionUID for the Variable interface has been made for backward compatibility with SNMP4J 1.7.x or earlier serialized Variable instances.

  • Method Summary

    Modifier and Type
    Method
    Description
    Object
    clone()
    Clones this variable.
    int
    compareTo(Variable o)
     
    boolean
    equals(Object o)
     
    void
    fromSubIndex(OID subIndex, boolean impliedLength)
    Sets the value of this Variable from the supplied (sub-)index.
    int
    getSyntax()
    Gets the ASN.1 syntax identifier value of this SNMP variable.
    String
    getSyntaxString()
    Gets a textual description of this Variable.
    int
    hashCode()
     
    boolean
    isDynamic()
    Indicates whether this variable is dynamic.
    boolean
    isException()
    Checks whether this variable represents an exception like noSuchObject, noSuchInstance, and endOfMibView.
    int
    toInt()
    Returns an integer representation of this variable if such a representation exists.
    long
    toLong()
    Returns a long representation of this variable if such a representation exists.
    String
    toString()
    Gets a string representation of the variable.
    OID
    toSubIndex(boolean impliedLength)
    Converts the value of this Variable to a (sub-)index value.

    Methods inherited from interface org.snmp4j.asn1.BERSerializable

    decodeBER, encodeBER, getBERLength, getBERPayloadLength

  • Field Details

    • serialVersionUID

      static final long serialVersionUID
      This definition of a serialVersionUID for the Variable interface has been made for backward compatibility with SNMP4J 1.7.x or earlier serialized Variable instances.
      See Also:

  • Method Details

    • equals

      boolean equals(Object o)
      Overrides:
      equals in class Object

    • compareTo

      int compareTo(Variable o)
      Specified by:
      compareTo in interface Comparable<Variable>

    • hashCode

      int hashCode()
      Overrides:
      hashCode in class Object

    • clone

      Object clone()
      Clones this variable. Cloning can be used by the SNMP4J API to better support concurrency by creating a clone for internal processing. The content of this object is independent to the content of the clone. Thus, changes to the clone will have no effect to this object.
      Returns:
      a new instance of this Variable with the same value.

    • getSyntax

      int getSyntax()
      Gets the ASN.1 syntax identifier value of this SNMP variable.
      Returns:
      an integer value < 128 for regular SMI objects and a value >= 128 for exception values like noSuchObject, noSuchInstance, and endOfMibView.

    • isException

      boolean isException()
      Checks whether this variable represents an exception like noSuchObject, noSuchInstance, and endOfMibView.
      Returns:
      true if the syntax of this variable is an instance of Null and its syntax equals one of the following:

    • toString

      String toString()
      Gets a string representation of the variable.
      Overrides:
      toString in class Object
      Returns:
      a string representation of the variable's value.

    • toInt

      int toInt()
      Returns an integer representation of this variable if such a representation exists.
      Returns:
      an integer value (if the native representation of this variable would be a long, then the long value will be casted to int).
      Throws:
      UnsupportedOperationException - if an integer representation does not exists for this Variable.

    • toLong

      long toLong()
      Returns a long representation of this variable if such a representation exists.
      Returns:
      a long value.
      Throws:
      UnsupportedOperationException - if a long representation does not exists for this Variable.

    • getSyntaxString

      String getSyntaxString()
      Gets a textual description of this Variable.
      Returns:
      a textual description like 'Integer32' as used in the Structure of Management Information (SMI) modules. '?' is returned if the syntax is unknown.

    • toSubIndex

      OID toSubIndex(boolean impliedLength)
      Converts the value of this Variable to a (sub-)index value.
      Parameters:
      impliedLength - specifies if the sub-index has an implied length. This parameter applies to variable length variables only (e.g. OctetString and OID). For other variables it has no effect.
      Returns:
      an OID that represents this value as an (sub-)index.
      Throws:
      UnsupportedOperationException - if this variable cannot be used in an index.

    • fromSubIndex

      void fromSubIndex(OID subIndex, boolean impliedLength)
      Sets the value of this Variable from the supplied (sub-)index.
      Parameters:
      subIndex - the sub-index OID.
      impliedLength - specifies if the sub-index has an implied length. This parameter applies to variable length variables only (e.g. OctetString and OID). For other variables it has no effect.
      Throws:
      UnsupportedOperationException - if this variable cannot be used in an index.

    • isDynamic

      boolean isDynamic()
      Indicates whether this variable is dynamic. If a variable is dynamic, precautions have to be taken when a Variable is serialized using BER encoding, because between determining the length with BERSerializable.getBERLength() for encoding enclosing SEQUENCES and the actual encoding of the Variable itself with BERSerializable.encodeBER(java.io.OutputStream) changes to the value need to be blocked by synchronization. In order to ensure proper synchronization if a Variable is dynamic, modifications of the variables content need to synchronize on the Variable instance. This can be achieved for the standard SMI Variable implementations for example by 
          public static modifyVariable(Integer32 variable, int value)
      synchronize(variable) {
        variable.setValue(value);
      }
    }
      Returns:
      true if the variable might change its value between two calls to BERSerializable.getBERLength() and BERSerializable.encodeBER(java.io.OutputStream) and false if the value is immutable or if its value does not change while serialization because of measures taken by the implementor (i.e. variable cloning).