org.rosuda.REngine
Class REXPNull

java.lang.Object
  org.rosuda.REngine.REXP
      org.rosuda.REngine.REXPNull

public class REXPNull
extends REXP

represents a NULL object in R.

Note: there is a slight asymmetry - in R NULL is represented by a zero-length pairlist. For this reason REXPNull returns true for isList() and asList() will return an empty list. Nonetheless REXPList of the length 0 will NOT return true in isNull() (currently), becasue it is considered a different object in Java. These nuances are still subject to change, because it's not clear how it should be treated. At any rate use REXPNull instead of empty REXPList if NULL is the intended value.

Field Summary

Fields inherited from class org.rosuda.REngine.REXP

attr, maxDebugItems

Constructor Summary

REXPNull()

REXPNull(REXPList attr)

Method Summary

RList	asList() returns the contents as a (named) list (if supported by the represented object)
java.lang.Object	asNativeJavaObject() attempt to represent the REXP by a native Java object and return it.
boolean	isList() check whether the REXP object is a list (either generic vector or a pairlist - i.e.
boolean	isNull() check whether the REXP object is NULL

Methods inherited from class org.rosuda.REngine.REXP

_attr, asBytes, asDouble, asDoubleMatrix, asDoubles, asFactor, asInteger, asIntegers, asString, asStrings, createDataFrame, createDoubleMatrix, dim, getAttribute, hasAttribute, inherits, isComplex, isEnvironment, isExpression, isFactor, isInteger, isLanguage, isLogical, isNA, isNumeric, isPairList, isRaw, isRecursive, isReference, isString, isSymbol, isVector, length, toDebugString, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

REXPNull

public REXPNull()

REXPNull

public REXPNull(REXPList attr)

Method Detail

isNull

public boolean isNull()

Description copied from class: REXP

check whether the REXP object is NULL

Overrides:

isNull in class REXP

Returns:

true if the receiver is NULL, false otherwise

isList

public boolean isList()

Description copied from class: REXP

check whether the REXP object is a list (either generic vector or a pairlist - i.e. REXP.asList() will succeed)

Overrides:

isList in class REXP

Returns:

true if the receiver is a generic vector or a pair-list, false otherwise

asList

public RList asList()

Description copied from class: REXP

returns the contents as a (named) list (if supported by the represented object)

Overrides:

asList in class REXP

asNativeJavaObject

public java.lang.Object asNativeJavaObject()

Description copied from class: REXP

attempt to represent the REXP by a native Java object and return it. Note that this may lead to loss of information (e.g., factors may be returned as a string array) and attributes are ignored. Not all R types can be converted to native Java objects. Also note that R has no concept of scalars, so vectors of length 1 will always be returned as an arrays (i.e., int[1] and not Integer).

Overrides:

asNativeJavaObject in class REXP