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.

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

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.

Example:

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

scala> val y = LinkedList(2)
y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

scala> val z = x ++: y
z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)

This overload exists because: for the implementation of ++: we should reuse that of ++ because many collections override it with more efficient versions.

Since TraversableOnce has no ++ method, we have to implement that directly, but Traversable and down can use the overload.

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.

Example:

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

scala> val y = LinkedList(2)
y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

scala> val z = x ++: y
z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)

A copy of the array with an element prepended.

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

Also, the original array 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)

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

Note: /: is alternate syntax for foldLeft; z /: xs is the same as xs foldLeft z.

Examples:

Note that the folding function used to compute b is equivalent to that used to compute c.

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

scala> val b = (5 /: a)(_+_)
b: Int = 15

scala> val c = (5 /: a)((x,y) => x + y)
c: Int = 15

A copy of this array with an element appended.

A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.

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)

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

Note: :\ is alternate syntax for foldRight; xs :\ z is the same as xs foldRight z.

Examples:

Note that the folding function used to compute b is equivalent to that used to compute c.

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

scala> val b = (a :\ 5)(_+_)
b: Int = 15

scala> val c = (a :\ 5)((x,y) => x + y)
c: Int = 15

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

Appends all elements of this mutable indexed sequence to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this mutable indexed 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 mutable indexed 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 mutable indexed 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 mutable indexed 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 mutable indexed 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)

Aggregates the results of applying an operator to subsequent elements.

This is a more general form of fold and reduce. It is similar to foldLeft in that it doesn't require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.

aggregate splits the mutable indexed sequence into partitions and processes each partition by sequentially applying seqop, starting with z (like foldLeft). Those intermediate results are then combined by using combop (like fold). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), so combop may be invoked an arbitrary number of times (even 0).

As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First, seqop transforms each input character to an Int and adds it to the sum (of the partition). Then, combop just needs to sum up the intermediate results of the partitions:

List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })

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).

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

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

Iterates over combinations. A _combination_ of length n is a subsequence of the original sequence, with the elements taken in order. Thus, "xy" and "yy" are both length-2 combinations of "xyy", but "yx" is not. If there is more than one way to generate the same subsequence, only one will be returned.

For example, "xyyy" has three different ways to generate "xy" depending on whether the first, second, or third "y" is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.

Tests whether this mutable indexed sequence contains a given value as an element.

Tests whether this mutable indexed sequence contains a given sequence as a slice.

Copies the elements of this array to an array. Fills the given array xs with at most len elements of this array, starting at position start. Copying will stop once either the end of the current array is reached, or the end of the target array is reached, or len elements have been copied.

Copies the elements of this array to an array. Fills the given array xs with values of this array. Copying will stop once either the end of the current array is reached, or the end of the target array is reached.

Copies the elements of this array to an array. Fills the given array xs with values of this array, beginning at index start. Copying will stop once either the end of the current array is reached, or the end of the target array is reached.

Copies all elements of this mutable indexed sequence to a buffer.

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

Counts the number of elements in the mutable indexed sequence which satisfy a predicate.

Creates a possible nested IndexedSeq which consists of all the elements of this array. If the elements are arrays themselves, the deep transformation is applied recursively to them. The stringPrefix of the IndexedSeq is "Array", hence the IndexedSeq prints like an array with all its elements shown, and the same recursively for any subarrays.

Example:

Array(Array(1, 2), Array(3, 4)).deep.toString

prints: Array(Array(1, 2), Array(3, 4))

Computes the multiset difference between this array and another sequence.

Builds a new mutable indexed sequence from this mutable indexed sequence without any duplicate elements.

Selects all elements except first n ones.

Selects all elements except last n ones.

Drops longest prefix of elements that satisfy a predicate.

Tests whether this mutable indexed sequence ends with the given sequence.

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.

Tests whether a predicate holds for at least one element of this mutable indexed sequence.

Selects all elements of this mutable indexed sequence which satisfy a predicate.

Selects all elements of this mutable indexed sequence which do not satisfy a predicate.

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 first element of the mutable indexed sequence satisfying a predicate, if any.

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

Folds the elements of this mutable indexed 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 a start value and all elements of this mutable indexed sequence, going left to right.

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

Tests whether a predicate holds for all elements of this mutable indexed sequence.

Applies a function f to all elements of this array.

Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.

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 mutable indexed sequence into a map of mutable indexed sequences according to some discriminator function.

Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new mutable indexed sequence.

Partitions elements in fixed size mutable indexed sequences.

Tests whether this mutable indexed sequence is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. Non-empty Iterators usually return false even if they were created from a collection with a known finite size.

Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns true. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.

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

Selects the first element of this mutable indexed sequence.

Optionally selects the first element.

Finds index of first occurrence of some value in this array after or at some start index.

Finds index of first occurrence of some value in this array.

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

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

Finds index of the first element satisfying some predicate after or at some start index.

Finds index of first element satisfying some predicate.

Produces the range of all indices of this sequence.

Selects all elements except the last.

Iterates over the inits of this mutable indexed sequence. The first value will be this mutable indexed sequence and the final one will be an empty mutable indexed sequence, with the intervening values the results of successive applications of init.

Computes the multiset intersection between this array and another sequence.

Tests whether this mutable indexed sequence contains given index.

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

Tests whether this mutable indexed sequence is empty.

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 mutable indexed sequence can be repeatedly traversed.

Creates a new iterator over all elements contained in this iterable object.

Selects the last element.

Finds index of last occurrence of some value in this array before or at a given end index.

Finds index of last occurrence of some value in this array.

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

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

Finds index of last element satisfying some predicate before or at given end index.

Finds index of last element satisfying some predicate.

Optionally selects the last element.

Compares the length of this mutable indexed sequence to a test value.

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

Finds the largest element.

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

Finds the smallest element.

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

Displays all elements of this mutable indexed sequence in a string.

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

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

Equivalent to !(this eq that).

Tests whether the mutable indexed sequence is not empty.

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.

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

Returns a parallel implementation of this collection.

For most collection types, this method creates a new parallel collection by copying all the elements. For these collection, par takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.

Specific collections (e.g. ParArray or mutable.ParHashMap) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections, par takes constant or sublinear time.

All parallel collections return a reference to themselves.

Partitions this mutable indexed sequence in two mutable indexed sequences according to a predicate.

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

Iterates over distinct permutations.

Returns the length of the longest prefix whose elements all satisfy some predicate.

Multiplies up the elements of this collection.

Reduces the elements of this mutable indexed 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 mutable indexed sequence, going left to right.

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

Reduces the elements of this mutable indexed 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 mutable indexed sequence, going right to left.

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

The collection of type mutable indexed sequence underlying this TraversableLike object. By default this is implemented as the TraversableLike object itself, but this can be overridden.

Returns new mutable indexed sequence with elements in reversed order.

An iterator yielding elements in reversed order.

Note: xs.reverseIterator is the same as xs.reverse.iterator but might be more efficient.

Builds a new collection by applying a function to all elements of this array and collecting the results in reversed order.

Note: xs.reverseMap(f) is the same as xs.reverse.map(f) but might be more efficient.

Checks if the other iterable collection contains the same elements in the same order as this array.

Computes a prefix scan of the elements of the collection.

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

Produces a collection containing cumulative results of applying the operator going left to right.

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

Example:

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

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

A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.

The size of this mutable indexed sequence, equivalent to length.

Selects an interval of elements. The returned collection is made up of all elements x which satisfy the invariant:

from <= indexOf(x) < until

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

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 mutable indexed sequence according to a comparison function.

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 mutable indexed sequence 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.

Splits this mutable indexed sequence into a prefix/suffix pair according to a predicate.

Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p), provided the evaluation of the predicate p does not cause any side-effects.

Splits this mutable indexed sequence into two at a given position. Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).

Tests whether this mutable indexed 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.

Tests whether this mutable indexed sequence starts with the given sequence.

Defines the prefix of this object's toString representation.

Sums up the elements of this collection.

Selects all elements except the first.

Iterates over the tails of this mutable indexed sequence. The first value will be this mutable indexed sequence and the final one will be an empty mutable indexed sequence, with the intervening values the results of successive applications of tail.

Selects first n elements.

Selects last n elements.

Takes longest prefix of elements that satisfy a predicate.

Converts this array into another by copying all elements.

Converts this array to an array.

Uses the contents of this mutable indexed sequence to create a new mutable buffer.

Converts this mutable indexed sequence to an indexed sequence.

Returns this mutable indexed sequence as an iterable collection.

A new collection will not be built; lazy collections will stay lazy.

Returns an Iterator over the elements in this mutable indexed sequence. Produces the same result as iterator.

Converts this mutable indexed sequence to a list.

Converts this array to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.

Converts this mutable indexed sequence to a sequence.

A new collection will not be built; in particular, lazy sequences will stay lazy.

Converts this mutable indexed sequence to a set.

Converts this mutable indexed sequence to a stream.

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.

Converts this mutable indexed sequence to an unspecified Traversable. Will return the same collection if this instance is already Traversable.

Converts this mutable indexed sequence to a Vector.

Transposes a two dimensional array.

Produces a new sequence which contains all elements of this array and also all elements of a given sequence. xs union ys is equivalent to xs ++ ys.

Another way to express this is that xs union ys computes the order-preserving multi-set union of xs and ys. union is hence a counter-part of diff and intersect which also work on multi-sets.

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

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

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 sub-sequence view starting at index from and extending up to (but not including) index until.

Creates a view of this iterable @see Iterable.View

Creates a non-strict filter of this mutable indexed sequence.

Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.

Returns a 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.

Returns a array formed from this array and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

Zips this array with its indices.

Selects an element by its index in the mutable indexed sequence.

Example:

scala> val x = List(1, 2, 3, 4, 5)
x: List[Int] = List(1, 2, 3, 4, 5)

scala> x(3)
res1: Int = 4

The equals method for arbitrary sequences. Compares this sequence to some other object.

Hashcodes for Array produce a value from the hashcodes of all the elements of the mutable indexed sequence.

The length of the mutable indexed sequence.

Note: xs.length and xs.size yield the same result.

Converts this mutable indexed sequence to a string.

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.

Replaces element at given index with a new value.