rJava (version 0.6-3)

jequals: Comparing Java References

Description

.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.

Usage

.jequals(a, b, strict = FALSE)

Arguments

a

first object

b

second object

strict

when set to TRUE then non-references save for NULL are always treated as different, see details.

Value

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

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.

See Also

is.jnull

Examples

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