AbstractVariable (SNMP4J 2.8.5)

java.lang.Object
- org.snmp4j.smi.AbstractVariable

All Implemented Interfaces:

Serializable, Cloneable, Comparable<Variable>, BERSerializable, Variable

Direct Known Subclasses:

Counter64, Integer32, Null, OctetString, OID, SMIAddress, UnsignedInteger32, VariantVariable
```
public abstract class AbstractVariable
extends Object
implements Variable, Serializable
```
The Variable abstract class is the base class for all SNMP variables.
All derived classes need to be registered with their SMI BER type in the smisyntaxes.propertiesso that the createFromBER(BERInputStream inputStream) method is able to decode a variable from a BER encoded stream.
To register additional syntaxes, set the system property SMISYNTAXES_PROPERTIES before decoding a Variable for the first time. The path of the property file must be accessible from the classpath and it has to be specified relative to the Variable class.

Since:

1.8

Version:

1.8

Author:

Frank Fock, Jochen Katz

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field and Description

static String SMISYNTAXES_PROPERTIES

Fields
Modifier and Type	Field and Description
`static String`	`SMISYNTAXES_PROPERTIES`

Constructor Summary

Constructors
Constructor and Description

AbstractVariable()
The abstract Variable class serves as the base class for all specific SNMP syntax types.

Constructors
Constructor and Description
`AbstractVariable()` The abstract `Variable` class serves as the base class for all specific SNMP syntax types.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`abstract Object`	`clone()` Clones this variable.
`abstract int`	`compareTo(Variable o)`
`static Variable`	`createFromBER(BERInputStream inputStream)` Creates a `Variable` from a BER encoded `BERInputStream`.
`static Variable`	`createFromSyntax(int smiSyntax)` Creates a `Variable` from the supplied SMI syntax identifier.
`abstract void`	`decodeBER(BERInputStream inputStream)` Decodes a `Variable` from an `BERInputStream`.
`abstract void`	`encodeBER(OutputStream outputStream)` Encodes a `Variable` to an `OutputStream`.
`static boolean`	`equal(AbstractVariable a, AbstractVariable b)` Tests if two variables have the same value.
`abstract boolean`	`equals(Object o)`
`abstract void`	`fromSubIndex(OID subIndex, boolean impliedLength)` Sets the value of this `Variable` from the supplied (sub-)index.
`abstract int`	`getBERLength()` Returns the length of this `Variable` in bytes when encoded according to the Basic Encoding Rules (BER).
`int`	`getBERPayloadLength()` Returns the length of the payload of this `BERSerializable` object in bytes when encoded according to the Basic Encoding Rules (BER).
`abstract int`	`getSyntax()` Gets the ASN.1 syntax identifier value of this SNMP variable.
`static int`	`getSyntaxFromString(String syntaxString)` Returns the BER syntax ID for the supplied syntax string (as returned by `getSyntaxString(int)`).
`String`	`getSyntaxString()` Gets a textual description of this Variable.
`static String`	`getSyntaxString(int syntax)` Gets a textual description of the supplied syntax type.
`abstract int`	`hashCode()`
`boolean`	`isDynamic()` Indicates whether this variable is dynamic, which means that it might change its value while it is being (BER) serialized.
`boolean`	`isException()` Checks whether this variable represents an exception like noSuchObject, noSuchInstance, and endOfMibView.
`abstract int`	`toInt()` Returns an integer representation of this variable if such a representation exists.
`abstract long`	`toLong()` Returns a long representation of this variable if such a representation exists.
`abstract String`	`toString()` Gets a string representation of the variable.
`abstract OID`	`toSubIndex(boolean impliedLength)` Converts the value of this `Variable` to a (sub-)index value.

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - SMISYNTAXES_PROPERTIES
```
public static final String SMISYNTAXES_PROPERTIES
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - AbstractVariable
```
public AbstractVariable()
```
    The abstract Variable class serves as the base class for all specific SNMP syntax types.
- Method Detail
  - equals
```
public abstract boolean equals(Object o)
```
    Specified by:
    
    equals in interface Variable
    
    Overrides:
    
    equals in class Object
  - compareTo
```
public abstract int compareTo(Variable o)
```
    Specified by:
    
    compareTo in interface Comparable<Variable>
    
    Specified by:
    
    compareTo in interface Variable
  - hashCode
```
public abstract int hashCode()
```
    Specified by:
    
    hashCode in interface Variable
    
    Overrides:
    
    hashCode in class Object
  - getBERLength
```
public abstract int getBERLength()
```
    Returns the length of this Variable in bytes when encoded according to the Basic Encoding Rules (BER).
    
    Specified by:
    
    getBERLength in interface BERSerializable
    
    Returns:
    
    the BER encoded length of this variable.
  - getBERPayloadLength
```
public int getBERPayloadLength()
```
    Description copied from interface: BERSerializable
    
    Returns the length of the payload of this BERSerializable object in bytes when encoded according to the Basic Encoding Rules (BER).
    
    Specified by:
    
    getBERPayloadLength in interface BERSerializable
    
    Returns:
    
    the BER encoded length of this variable.
  - decodeBER
```
public abstract void decodeBER(BERInputStream inputStream)
                        throws IOException
```
    Decodes a Variable from an BERInputStream.
    
    Specified by:
    
    decodeBER in interface BERSerializable
    
    Parameters:
    
    inputStream - an BERInputStream containing a BER encoded byte stream.
    
    Throws:
    
    IOException - if the stream could not be decoded by using BER rules.
  - encodeBER
```
public abstract void encodeBER(OutputStream outputStream)
                        throws IOException
```
    Encodes a Variable to an OutputStream.
    
    Specified by:
    
    encodeBER in interface BERSerializable
    
    Parameters:
    
    outputStream - an OutputStream.
    
    Throws:
    
    IOException - if an error occurs while writing to the stream.
  - createFromBER
```
public static Variable createFromBER(BERInputStream inputStream)
                              throws IOException
```
    Creates a Variable from a BER encoded BERInputStream. Subclasses of Variable are registered using the properties file smisyntaxes.properties in this package. The properties are read when this method is called first.
    
    Parameters:
    
    inputStream - an BERInputStream containing a BER encoded byte stream.
    
    Returns:
    
    an instance of a subclass of Variable.
    
    Throws:
    
    IOException - if the inputStream is not properly BER encoded.
  - createFromSyntax
```
public static Variable createFromSyntax(int smiSyntax)
```
    Creates a Variable from the supplied SMI syntax identifier. Subclasses of Variable are registered using the properties file smisyntaxes.properties in this package. The properties are read when this method is called for the first time.
    
    Parameters:
    
    smiSyntax - an SMI syntax identifier of the registered types, which is typically defined by SMIConstants.
    
    Returns:
    
    a Variable variable instance of the supplied SMI syntax.
  - getSyntax
```
public abstract int getSyntax()
```
    Gets the ASN.1 syntax identifier value of this SNMP variable.
    
    Specified by:
    
    getSyntax in interface Variable
    
    Returns:
    
    an integer value less than 128 for regular SMI objects and a value greater or equal than 128 for exception values like noSuchObject, noSuchInstance, and endOfMibView.
  - isException
```
public boolean isException()
```
    Checks whether this variable represents an exception like noSuchObject, noSuchInstance, and endOfMibView.
    Specified by:
    
    isException in interface Variable
    
    Returns:
    true if the syntax of this variable is an instance of Null and its syntax equals one of the following:
    
    SMIConstants.EXCEPTION_NO_SUCH_OBJECT
    
    SMIConstants.EXCEPTION_NO_SUCH_INSTANCE
    
    SMIConstants.EXCEPTION_END_OF_MIB_VIEW
  - toString
```
public abstract String toString()
```
    Gets a string representation of the variable.
    
    Specified by:
    
    toString in interface Variable
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    a string representation of the variable's value.
  - toInt
```
public abstract int toInt()
```
    Returns an integer representation of this variable if such a representation exists.
    
    Specified by:
    
    toInt in interface Variable
    
    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.
    
    Since:
    
    1.7
  - toLong
```
public abstract long toLong()
```
    Returns a long representation of this variable if such a representation exists.
    
    Specified by:
    
    toLong in interface Variable
    
    Returns:
    
    a long value.
    
    Throws:
    
    UnsupportedOperationException - if a long representation does not exists for this Variable.
    
    Since:
    
    1.7
  - clone
```
public abstract Object clone()
```
    Description copied from interface: Variable
    
    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.
    
    Specified by:
    
    clone in interface Variable
    
    Overrides:
    
    clone in class Object
    
    Returns:
    
    a new instance of this Variable with the same value.
  - getSyntaxString
```
public static String getSyntaxString(int syntax)
```
    Gets a textual description of the supplied syntax type.
    
    Parameters:
    
    syntax - the BER code of the syntax.
    
    Returns:
    
    a textual description like 'Integer32' for syntax as used in the Structure of Management Information (SMI) modules. '?' is returned if the supplied syntax is unknown.
  - getSyntaxString
```
public final String getSyntaxString()
```
    Gets a textual description of this Variable.
    
    Specified by:
    
    getSyntaxString in interface Variable
    
    Returns:
    
    a textual description like 'Integer32' as used in the Structure of Management Information (SMI) modules. '?' is returned if the syntax is unknown.
    
    Since:
    
    1.7
  - getSyntaxFromString
```
public static int getSyntaxFromString(String syntaxString)
```
    Returns the BER syntax ID for the supplied syntax string (as returned by getSyntaxString(int)).
    
    Parameters:
    
    syntaxString - the textual representation of the syntax.
    
    Returns:
    
    the corresponding BER ID.
    
    Since:
    
    1.6
  - toSubIndex
```
public abstract OID toSubIndex(boolean impliedLength)
```
    Converts the value of this Variable to a (sub-)index value.
    
    Specified by:
    
    toSubIndex in interface Variable
    
    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.
    
    Since:
    
    1.7
  - fromSubIndex
```
public abstract void fromSubIndex(OID subIndex,
                                  boolean impliedLength)
```
    Sets the value of this Variable from the supplied (sub-)index.
    
    Specified by:
    
    fromSubIndex in interface Variable
    
    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.
    
    Since:
    
    1.7
  - isDynamic
```
public boolean isDynamic()
```
    Indicates whether this variable is dynamic, which means that it might change its value while it is being (BER) serialized. If a variable is dynamic, it will be cloned on-the-fly when it is added to a PDU with PDU.add(VariableBinding). By cloning the value, it is ensured that there are no inconsistent changes between determining the length with getBERLength() for encoding enclosing SEQUENCES and the actual encoding of the Variable itself with encodeBER(java.io.OutputStream).
    
    Specified by:
    
    isDynamic in interface Variable
    
    Returns:
    
    false by default. Derived classes may override this if implementing dynamic Variable instances.
    
    Since:
    
    1.8
  - equal
```
public static boolean equal(AbstractVariable a,
                            AbstractVariable b)
```
    Tests if two variables have the same value.
    
    Parameters:
    
    a - a variable.
    
    b - another variable.
    
    Returns:
    
    true if a == null) ? (b == null) : a.equals(b).
    
    Since:
    
    2.0

Class AbstractVariable

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SMISYNTAXES_PROPERTIES

Constructor Detail

AbstractVariable

Method Detail

equals

compareTo

hashCode

getBERLength

getBERPayloadLength

decodeBER

encodeBER

createFromBER

createFromSyntax

getSyntax

isException

toString

toInt

toLong

clone

getSyntaxString

getSyntaxString

getSyntaxFromString

toSubIndex

fromSubIndex

isDynamic

equal