This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence
This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence.
The default implementations of this method is an equivalence relation:
x
of type Any
,
x.equals(x)
should return true
.x
and y
of type
Any
, x.equals(y)
should return true
if and only
if y.equals(x)
returns true
.x
, y
, and z
of type AnyRef
if x.equals(y)
returns true
and
y.equals(z)
returns
true
, then x.equals(z)
should return true
.
If you override this method, you should verify that
your implementation remains an equivalence relation.
Additionally, when overriding this method it is often necessary to
override hashCode
to ensure that objects that are
"equal" (o1.equals(o2)
returns true
)
hash to the same Int
(o1.hashCode.equals(o2.hashCode)
).
the object to compare against this object for equality.
true
if the receiver object is equivalent to the argument; false
otherwise.
The time when execution of this program started
The time when execution of this program started.
Returns a hash code value for the object
Returns a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash
codes (o1.hashCode.equals(o2.hashCode)
) yet not be
equal (o1.equals(o2)
returns false
). A
degenerate implementation could always return 0
.
However, it is required that if two objects are equal
(o1.equals(o2)
returns true
) that they
have identical hash codes
(o1.hashCode.equals(o2.hashCode)
). Therefore, when
overriding this method, be sure to verify that the behavior is
consistent with the equals
method.
The default main method
The default main method.
the arguments passed to the main method
Returns a string representation of the object
Returns a string representation of the object.
The default representation is platform dependent.
The
Application
trait can be used to quickly turn objects into executable programs, but is not recommended. Here is an example:Here, object
Main
inherits themain
method ofApplication
. The body of theMain
object defines the main program. This technique does not work if the main program depends on command-line arguments (which are not accessible with the technique presented here).It is possible to time the execution of objects that inherit from class
Application
by setting the globalscala.time
property. Here is an example for benchmarking objectMain
:In practice the
Application
trait has a number of serious pitfalls:object
extendingApplication
takes place during static initialization, concurrent code will always deadlock if it must synchronize with the enclosing object.object
extendingApplication
is run as part of the static initialization which occurs beforeApplication
'smain
method even begins execution.object
extendingApplication
. This can lead to a significant performance degradation.Instead, it is recommended to define a
main
method explicitly: