Class scala.Array

Test two objects for inequality.

Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

Alias for concat

Alias for prependedAll

Alias for prepended.

Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Alias for appended

Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

Alias for appendedAll

The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

Appends all elements of this immutable sequence to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this immutable sequence without any separator string.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> val h = a.addString(b)
h: StringBuilder = 1234

Appends all elements of this immutable sequence to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this immutable sequence, separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4

Appends all elements of this immutable sequence to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this immutable sequence are separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)

Composes this partial function with another partial function that gets applied to results of this partial function.

Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. It is highly recommended to call applyOrElse instead of isDefinedAt / apply for efficiency.

Composes this partial function with a transformation function that gets applied to results of this partial function.

If the runtime type of the function is a PartialFunction then the other andThen method is used (note its cautions).

A copy of this array with an element appended.

A copy of this immutable sequence with an element appended.

Note: will not terminate for infinite-sized collections.

Example:

scala> val a = List(1)
a: List[Int] = List(1)

scala> val b = a :+ 2
b: List[Int] = List(1, 2)

scala> println(a)
List(1)

A copy of this array with all elements of an array appended.

A copy of this array with all elements of a collection appended.

Returns a new immutable sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the immutable sequence is the most specific superclass encompassing the element types of the two operands.

The element at given index.

Indices start at 0; xs.apply(0) is the first element of array xs. Note the indexing syntax xs(i) is a shorthand for xs.apply(i).

Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.

Note that expression pf.applyOrElse(x, default) is equivalent to

if(pf isDefinedAt x) pf(x) else default(x)

except that applyOrElse method can be implemented more efficiently. For all partial function literals the compiler generates an applyOrElse implementation which avoids double evaluation of pattern matchers and guards. This makes applyOrElse the basis for the efficient implementation for many operations and scenarios, such as:

combining partial functions into orElse/andThen chains does not lead to excessive apply/isDefinedAt evaluation lift and unlift do not evaluate source functions twice on each invocation runWith allows efficient imperative-style combining of partial functions with conditionally applied actions

For non-literal partial function classes with nontrivial isDefinedAt method it is recommended to override applyOrElse with custom implementation that avoids double isDefinedAt evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.

Cast the receiver object to be of type T0.

Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.

Clone the Array.

Builds a new array by applying a partial function to all elements of this array on which the function is defined.

Builds a new immutable sequence by applying a partial function to all elements of this immutable sequence on which the function is defined.

Finds the first element of the array for which the given partial function is defined, and applies the partial function to it.

Finds the first element of the immutable sequence for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite-sized collections.

Composes another partial function k with this partial function so that this partial function gets applied to results of k.

Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. It is highly recommended to call applyOrElse instead of isDefinedAt / apply for efficiency.

Composes two instances of Function1 in a new Function1, with this function applied last.

Returns a new immutable sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the immutable sequence is the most specific superclass encompassing the element types of the two operands.

Tests whether this immutable sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

Copy elements of this array to another array. Fills the given array xs starting at index start with at most len values. Copying will stop once either all the elements of this array have been copied, or the end of the array is reached, or len elements have been copied.

Copy elements of this array to another array. Fills the given array xs starting at index start. Copying will stop once either all the elements of this array have been copied, or the end of the array is reached.

Copy elements of this array to another array. Fills the given array xs starting at index 0. Copying will stop once either all the elements of this array have been copied, or the end of the array is reached.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with at most len elements of this immutable sequence.

Copying will stop once either all the elements of this immutable sequence have been copied, or the end of the array is reached, or len elements have been copied.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this immutable sequence.

Copying will stop once either all the elements of this immutable sequence have been copied, or the end of the array is reached.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this immutable sequence.

Copying will stop once either all the elements of this immutable sequence have been copied, or the end of the array is reached.

Tests whether every element of this immutable sequence relates to the corresponding element of another sequence by satisfying a test predicate.

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Computes the multiset difference between this array and another sequence.

Computes the multiset difference between this immutable sequence and another sequence.

Selects all the elements of this array ignoring the duplicates as determined by == after applying the transforming function f.

Selects all the elements of this immutable sequence ignoring the duplicates as determined by == after applying the transforming function f.

Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.

The empty iterable of the same type as this iterable

Tests whether this array ends with the given sequence.

Tests whether this array ends with the given array.

Tests whether this immutable sequence ends with the given sequence.

Note: will not terminate for infinite-sized collections.

Tests whether the argument (that) is a reference to the receiver object (this).

The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:

It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false. null.eq(null) returns true.

When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

The equality method for reference types. Default implementation delegates to eq.

See also equals in scala.Any.

Called by the garbage collector on the receiver object when there are no more references to the object.

The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

Finds the last element of the immutable sequence satisfying a predicate, if any.

Note: will not terminate for infinite-sized collections.

Builds a new array by applying a function to all elements of this array and using the elements of the resulting collections.

Builds a new immutable sequence by applying a function to all elements of this immutable sequence and using the elements of the resulting collections.

For example:

def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")

The type of the resulting collection is guided by the static type of immutable sequence. This might cause unexpected results sometimes. For example:

// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)

// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq)

// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)

// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)

Flattens a two-dimensional array by concatenating all its rows into a single array.

Converts this immutable sequence of traversable collections into a immutable sequence formed by the elements of these traversable collections.

The resulting collection's type will be guided by the type of immutable sequence. For example:

val xs = List(
           Set(1, 2, 3),
           Set(1, 2, 3)
         ).flatten
// xs == List(1, 2, 3, 1, 2, 3)

val ys = Set(
           List(1, 2, 3),
           List(3, 2, 1)
         ).flatten
// ys == Set(1, 2, 3)

Folds the elements of this array using the specified associative binary operator.

Folds the elements of this immutable sequence using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Note: will not terminate for infinite-sized collections.

Applies a binary operator to a start value and all elements of this array, going left to right.

Applies a binary operator to a start value and all elements of this immutable sequence, going left to right.

Note: will not terminate for infinite-sized collections.

Applies a binary operator to all elements of this array and a start value, going right to left.

Applies a binary operator to all elements of this immutable sequence and a start value, going right to left.

Note: will not terminate for infinite-sized collections.

Apply f to each element for its side effects. Note: [U] parameter needed to help scalac's type inference.

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

Returns the runtime class representation of the object.

Partitions this array into a map of arrays according to some discriminator function.

Partitions this immutable sequence into a map of immutable sequences according to some discriminator function.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Partitions this array into a map of arrays according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.

It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.

case class User(name: String, age: Int)

def namesByAge(users: Array[User]): Map[Int, Array[String]] =
  users.groupMap(_.age)(_.name)

Partitions this immutable sequence into a map of immutable sequences according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.

It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.

case class User(name: String, age: Int)

def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
  users.groupMap(_.age)(_.name)

Note: Even when applied to a view or a lazy collection it will always force the elements.

Partitions this immutable sequence into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the value function and then reduced into a single value with the reduce function.

It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.

def occurrences[A](as: Seq[A]): Map[A, Int] =
  as.groupMapReduce(identity)(_ => 1)(_ + _)

Note: Even when applied to a view or a lazy collection it will always force the elements.

The hashCode method for reference types. See hashCode in scala.Any.

Finds index of first occurrence of some value in this immutable sequence.

Finds first index where this immutable sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

Finds first index after or at a start index where this immutable sequence contains a given sequence as a slice.

Note: may not terminate for infinite-sized collections.

Finds index of the first element satisfying some predicate.

Note: may not terminate for infinite-sized collections.

Computes the multiset intersection between this array and another sequence.

Computes the multiset intersection between this immutable sequence and another sequence.

Tests whether this immutable sequence contains given index.

The implementations of methods apply and isDefinedAt turn a Seq[A] into a PartialFunction[Int, A].

Test whether the dynamic type of the receiver object is T0.

Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

Tests whether this immutable sequence can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.

The companion object of this immutable sequence, providing various factory methods.

Finds last index where this immutable sequence contains a given sequence as a slice.

Note: will not terminate for infinite-sized collections.

Finds last index before or at a given end index where this immutable sequence contains a given sequence as a slice.

Note: will not terminate for infinite-sized collections.

Finds index of last element satisfying some predicate.

Note: will not terminate for infinite-sized collections.

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.

val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.

val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)

Compares the length of this immutable sequence to the size of another Iterable.

Turns this partial function into a plain function returning an Option result.

Builds a new array by applying a function to all elements of this array.

Builds a new immutable sequence by applying a function to all elements of this immutable sequence.

Finds the largest element.

Finds the first element which yields the largest value measured by function f.

Finds the first element which yields the largest value measured by function f.

Finds the largest element.

Finds the smallest element.

Finds the first element which yields the smallest value measured by function f.

Finds the first element which yields the smallest value measured by function f.

Finds the smallest element.

Displays all elements of this immutable sequence in a string.

Delegates to addString, which can be overridden.

Displays all elements of this immutable sequence in a string using a separator string.

Delegates to addString, which can be overridden.

Displays all elements of this immutable sequence in a string using start, end, and separator strings.

Delegates to addString, which can be overridden.

Equivalent to !(this eq that).

Wakes up a single thread that is waiting on the receiver object's monitor.

Wakes up all threads that are waiting on the receiver object's monitor.

Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.

A copy of this array with an element value appended until a given target length is reached.

A copy of this immutable sequence with an element value appended until a given target length is reached.

Applies a function f to each element of the array and returns a pair of arrays: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Example:

val xs = Array(1, "one", 2, "two", 3, "three") partitionMap {
 case i: Int => Left(i)
 case s: String => Right(s)
}
// xs == (Array(1, 2, 3),
//        Array(one, two, three))

Applies a function f to each element of the immutable sequence and returns a pair of immutable sequences: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Example:

val xs = `immutable.Seq`(1, "one", 2, "two", 3, "three") partitionMap {
 case i: Int => Left(i)
 case s: String => Right(s)
}
// xs == (`immutable.Seq`(1, 2, 3),
//        `immutable.Seq`(one, two, three))

Returns a copy of this array with patched values. Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original array appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.

Produces a new immutable sequence where a slice of elements in this immutable sequence is replaced by another sequence.

Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original immutable sequence appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.

A copy of this array with an element prepended.

A copy of the immutable sequence with an element prepended.

Also, the original immutable sequence is not modified, so you will want to capture the result.

Example:

scala> val x = List(1)
x: List[Int] = List(1)

scala> val y = 2 +: x
y: List[Int] = List(2, 1)

scala> println(x)
List(1)

A copy of this array with all elements of an array prepended.

A copy of this array with all elements of a collection prepended.

As with :++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

It differs from :++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

Multiplies up the elements of this collection.

Reduces the elements of this immutable sequence using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Applies a binary operator to all elements of this immutable sequence, going left to right.

Note: will not terminate for infinite-sized collections.

Optionally applies a binary operator to all elements of this immutable sequence, going left to right.

Note: will not terminate for infinite-sized collections.

Reduces the elements of this immutable sequence, if any, using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Applies a binary operator to all elements of this immutable sequence, going right to left.

Note: will not terminate for infinite-sized collections.

Optionally applies a binary operator to all elements of this immutable sequence, going right to left.

Note: will not terminate for infinite-sized collections.

Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.

Note that expression pf.runWith(action)(x) is equivalent to

if(pf isDefinedAt x) { action(pf(x)); true } else false

except that runWith is implemented via applyOrElse and thus potentially more efficient. Using runWith avoids double evaluation of pattern matchers and guards for partial function literals.

Are the elements of this collection the same (and in the same order) as those of that?

Computes a prefix scan of the elements of the array.

Note: The neutral element z may be applied more than once.

Computes a prefix scan of the elements of the collection.

Note: The neutral element z may be applied more than once.

Produces an array containing cumulative results of applying the binary operator going left to right.

Produces a immutable sequence containing cumulative results of applying the operator going left to right, including the initial value.

Note: will not terminate for infinite-sized collections.

Produces an array containing cumulative results of applying the binary operator going right to left.

Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Example:

List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)

Search within an interval in this sorted sequence for a specific element. If this sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.

The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.

Search this sorted sequence for a specific element. If the sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.

The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.

Computes length of longest segment whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

Computes length of longest segment whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

Compares the size of this immutable sequence to the size of another Iterable.

Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.) The "sliding window" step is set to one.

Sorts this array according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

Sorts this immutable sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

The sort is stable. That is, elements that are equal (as determined by ord.compare) appear in the same order in the sorted sequence as in the original.

Sorts this array according to an Ordering.

The sort is stable. That is, elements that are equal (as determined by lt) appear in the same order in the sorted sequence as in the original.

Sorts this immutable sequence according to an Ordering.

The sort is stable. That is, elements that are equal (as determined by ord.compare) appear in the same order in the sorted sequence as in the original.

Tests whether this array contains the given sequence at a given index.

Tests whether this array contains the given array at a given index.

Tests whether this array starts with the given array.

Tests whether this immutable sequence contains the given sequence at a given index.

Note: If the both the receiver object this and the argument that are infinite sequences this method may not terminate.

Returns a Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

For collections of Int, Short, Byte or Char, an IntStepper is returnedFor collections of Double or Float, a DoubleStepper is returnedFor collections of Long a LongStepper is returnedFor any other element type, an AnyStepper is returned

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

Sums up the elements of this collection.

Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:

xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]

Create a copy of this array with the specified element type.

Convert collection to array.

Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

Transposes a two dimensional array.

Transposes this immutable sequence of iterable collections into a immutable sequence of immutable sequences.

The resulting collection's type will be guided by the static type of immutable sequence. For example:

val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))

Note: Even when applied to a view or a lazy collection it will always force the elements.

Tries to extract a B from an A in a pattern matching expression.

Converts an array of pairs into an array of first elements and an array of second elements.

Converts this immutable sequence of pairs into two collections of the first and second half of each pair.

val xs = `immutable.Seq`(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (`immutable.Seq`(1, 2, 3),
//        `immutable.Seq`(one, two, three))

Converts an array of triples into three arrays, one containing the elements from each position of the triple.

Converts this immutable sequence of triples into three collections of the first, second, and third element of each triple.

val xs = `immutable.Seq`(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (`immutable.Seq`(1, 2, 3),
//        `immutable.Seq`(one, two, three),
//        `immutable.Seq`(1, 2, 3))

Update the element at given index.

Indices start at 0; xs.update(i, x) replaces the i^th element in the array. Note the syntax xs(i) = x is a shorthand for xs.update(i, x).

A copy of this array with one single replaced element.

A copy of this immutable sequence with one single replaced element.

Returns an array formed from this array and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.