Comparing Java References

.jequals function can be used to determine whether two objects are equal. In addition, it allows mixed comparison of non-Java object for convenience, unless strict comparison is desired.

The binary operators == and != are mapped to (non-strict) call to .jequals for convenience.

.jequals(a, b, strict = FALSE)
first object
second object
when set to TRUE then non-references save for NULL are always treated as different, see details.

Comparing two Java objects is performed by calling equals method of one of the objects and passing the other object as its argument. This allows Java objects to define the `equality' in object-dependent way.

In addition, .jequals allows the comparison of Java object to other scalar R objects. This is done by creating a temporary Java object that corresponds to the R object and using it for a call to the equals method. If such conversion is not possible a warning is produced and the result it FALSE. The automatic conversion will be avoided if strict parameter is set to TRUE.

NULL values in a or b are replaced by Java null-references and thus .jequals(NULL,NULL) is TRUE.

If neither a and b are Java objects (with the exception of both being NULL) then the result is identical to that of all.equal(a,b). Neither comparison operators nor .jequals supports vectors and returns FALSE in that case. A warning is also issued unless strict comparison was requested.


  • TRUE if both object are considered equal, FALSE otherwise.


Don't use x == NULL to check for null-references, because x could be NULL and thus the result would be an empty vector. Use is.jnull instead. (In theory is.jnull and x == .jnull() are the the same, but is.jnull is more efficient.)

See Also


  • .jequals
  • !=,ANY,jobjRef-method
  • !=,jobjRef,jobjRef-method
  • !=,jobjRef,ANY-method
  • ==,ANY,jobjRef-method
  • ==,jobjRef,jobjRef-method
  • ==,jobjRef,ANY-method
s <- .jnew("java/lang/String", "foo")
.jequals(s, "foo") # TRUE
.jequals(s, "foo", strict=TRUE) # FALSE - "foo" is not a Java object
t <- s
.jequals(s, t, strict=TRUE) # TRUE

s=="foo" # TRUE
Documentation reproduced from package rJava, version 0.5-1, License: GPL version 2

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