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## java.util
Class Iterator

Method Summary
`boolean` | `asBoolean()` Coerce an iterator instance to a boolean value.
`Number` | `count(Object value)` Counts the number of occurrences of the given value from the items within this Iterator.
`Object` | `getAt(int idx)` Support the subscript operator for an Iterator.
`Object` | `inject(Object value, Closure closure)` Iterates through the given Iterator, passing in the initial value to the closure along with the first item.
`Iterator` | `iterator()` An identity function for iterators, supporting 'duck-typing' when trying to get an iterator for each object within a collection, some of which may already be iterators.
`String` | `join(String separator)` Concatenates the `toString()` representation of each item from the iterator, with the given String as a separator between each item.
`Object` | `max()` Adds max() method to Iterator objects.
`Object` | `max(Closure closure)` Selects the maximum value found from the Iterator using the closure to determine the correct ordering.
`Object` | `max(Comparator comparator)` Selects the maximum value found from the Iterator using the given comparator.
`Object` | `min()` Adds min() method to Iterator objects.
`Object` | `min(Comparator comparator)` Selects the minimum value found from the Iterator using the given comparator.
`Object` | `min(Closure closure)` Selects the minimum value found from the Iterator using the closure to determine the correct ordering.
`Iterator` | `reverse()` Reverses the iterator.
`int` | `size()` Provide the standard Groovy `size()` method for `Iterator`.
`Iterator` | `sort()` Sorts the given iterator items into a sorted iterator.
`Iterator` | `sort(Comparator comparator)` Sorts the given iterator items into a sorted iterator using the comparator.
`Iterator` | `sort(Closure closure)` Sorts the given iterator items into a sorted iterator using the Closure to determine the correct ordering.
`Object` | `sum()` Sums the items from an Iterator.
`Object` | `sum(Object initialValue)` Sums the items from an Iterator, adding the result to some initial value.
`Object` | `sum(Closure closure)` Sums the result of apply a closure to each item returned from an iterator.
`Object` | `sum(Object initialValue, Closure closure)` Sums the result of applying a closure to each item of an Iterator to some initial value.
`List` | `toList()` Convert an iterator to a List.
`Iterator` | `unique()` Returns an iterator equivalent to this iterator all duplicated items removed by using the default comparator.
`Iterator` | `unique(Closure closure)` Returns an iterator equivalent to this iterator but with all duplicated items removed by using a Closure to determine duplicate (equal) items.
`Iterator` | `unique(Comparator comparator)` Returns an iterator equivalent to this iterator with all duplicated items removed by using the supplied comparator.

Method Detail

### asBoolean

    public boolean asBoolean()

  Coerce an iterator instance to a boolean value. An iterator is coerced to false if there are no more elements to iterate over, and to true otherwise.

Returns:
  the boolean value

Since:
  1.7.0

### count

    public Number count(Object value)

  Counts the number of occurrences of the given value from the items within this Iterator. Comparison is done using Groovy's == operator (using `compareTo(value) == 0` or `equals(value)` ). The iterator will become exhausted of elements after determining the count value.

Parameters:
  `value` - the value being searched for.

Returns:
  the number of occurrences

Since:
  1.5.0

### getAt

    public Object getAt(int idx)

  Support the subscript operator for an Iterator. The iterator will be partially exhausted up until the idx entry after returning if a +ve or 0 idx is used, or fully exhausted if a -ve idx is used or no corresponding entry was found. Typical usage:

      def iter = [2, "a", 5.3].iterator()
      assert iter[1] == "a"

  A more elaborate example:

      def items = [2, "a", 5.3]
      def iter = items.iterator()
      assert iter[-1] == 5.3
      // iter exhausted, so reset
      iter = items.iterator()
      assert iter[1] == "a"
      // iter partially exhausted so now idx starts after "a"
      assert iter[0] == 5.3

Parameters:
  `idx` - an index value (-self.size() <= idx < self.size()).

Returns:
  the value at the given index (after normalisation) or null if no corresponding value was found

Since:
  1.7.2

### inject

    public Object inject(Object value, Closure closure)

  Iterates through the given Iterator, passing in the initial value to the closure along with the first item. The result is passed back (injected) into the closure along with the second item. The new result is injected back into the closure along with the third item and so on until the Iterator has been expired of values. Also known as foldLeft in functional parlance.

Parameters:
  `value` - a value.
  `closure` - a closure.

Returns:
  the last value of the last iteration

Since:
  1.5.0

### iterator

    public Iterator iterator()

  An identity function for iterators, supporting 'duck-typing' when trying to get an iterator for each object within a collection, some of which may already be iterators.

Returns:
  itself

Since:
  1.5.0

### join

    public String join(String separator)

  Concatenates the `toString()` representation of each item from the iterator, with the given String as a separator between each item. The iterator will become exhausted of elements after determining the resulting conjoined value.

Parameters:
  `separator` - a String separator.

Returns:
  the joined String

Since:
  1.5.5

### max

    public Object max()

  Adds max() method to Iterator objects. The iterator will become exhausted of elements after determining the maximum value.

Returns:
  the maximum value

Since:
  1.5.5

See:
  GroovyCollections#max.

### max

    public Object max(Closure closure)

  Selects the maximum value found from the Iterator using the closure to determine the correct ordering. The iterator will become exhausted of elements after this operation. If the closure has two parameters it is used like a traditional Comparator. I.e. it should compare its two parameters for order, returning a negative integer, zero, or a positive integer when the first parameter is less than, equal to, or greater than the second respectively. Otherwise, the Closure is assumed to take a single parameter and return a Comparable (typically an Integer) which is then used for further comparison.

Parameters:
  `closure` - a Closure used to determine the correct ordering.

Returns:
  the maximum value

Since:
  1.5.5

See:
  Collection#max.

### max

    public Object max(Comparator comparator)

  Selects the maximum value found from the Iterator using the given comparator.

Parameters:
  `comparator` - a Comparator.

Returns:
  the maximum value

Since:
  1.5.5

### min

    public Object min()

  Adds min() method to Iterator objects. The iterator will become exhausted of elements after determining the minimum value.

Returns:
  the minimum value

Since:
  1.5.5

See:
  Collection#min.

### min

    public Object min(Comparator comparator)

  Selects the minimum value found from the Iterator using the given comparator.

Parameters:
  `comparator` - a Comparator.

Returns:
  the minimum value

Since:
  1.5.5

See:
  Collection#min.

### min

    public Object min(Closure closure)

  Selects the minimum value found from the Iterator using the closure to determine the correct ordering. The iterator will become exhausted of elements after this operation. If the closure has two parameters it is used like a traditional Comparator. I.e. it should compare its two parameters for order, returning a negative integer, zero, or a positive integer when the first parameter is less than, equal to, or greater than the second respectively. Otherwise, the Closure is assumed to take a single parameter and return a Comparable (typically an Integer) which is then used for further comparison.

Parameters:
  `closure` - a Closure used to determine the correct ordering.

Returns:
  the minimum value

Since:
  1.5.5

See:
  Collection#min.

### reverse

    public Iterator reverse()

  Reverses the iterator. The original iterator will become exhausted of elements after determining the reversed values. A new iterator for iterating through the reversed values is returned.

Returns:
  a reversed Iterator

Since:
  1.5.5

### size

    public int size()

  Provide the standard Groovy `size()` method for `Iterator`. The iterator will become exhausted of elements after determining the size value.

Returns:
  the length of the Iterator

Since:
  1.5.5

### sort

    public Iterator sort()

  Sorts the given iterator items into a sorted iterator. The items are assumed to be comparable. The original iterator will become exhausted of elements after completing this method call. A new iterator is produced that traverses the items in sorted order.

Returns:
  the sorted items as an Iterator

Since:
  1.5.5

### sort

    public Iterator sort(Comparator comparator)

  Sorts the given iterator items into a sorted iterator using the comparator.

Parameters:
  `comparator` - a Comparator used for comparing items.

Returns:
  the sorted items as an Iterator

Since:
  1.5.5

### sort

    public Iterator sort(Closure closure)

  Sorts the given iterator items into a sorted iterator using the Closure to determine the correct ordering. The original iterator will be fully processed after the method call. If the closure has two parameters it is used like a traditional Comparator. I.e. it should compare its two parameters for order, returning a negative integer, zero, or a positive integer when the first parameter is less than, equal to, or greater than the second respectively. Otherwise, the Closure is assumed to take a single parameter and return a Comparable (typically an Integer) which is then used for further comparison.

Parameters:
  `closure` - a Closure used to determine the correct ordering.

Returns:
  the sorted items as an Iterator

Since:
  1.5.5

### sum

    public Object sum()

  Sums the items from an Iterator. This is equivalent to invoking the "plus" method on all items from the Iterator. The iterator will become exhausted of elements after determining the sum value.

Returns:
  The sum of all of the items

Since:
  1.5.5

### sum

    public Object sum(Object initialValue)

  Sums the items from an Iterator, adding the result to some initial value. This is equivalent to invoking the "plus" method on all items from the Iterator. The iterator will become exhausted of elements after determining the sum value.

Parameters:
  `initialValue` - the items in the collection will be summed to this initial value.

Returns:
  The sum of all of the items

Since:
  1.5.5

### sum

    public Object sum(Closure closure)

  Sums the result of apply a closure to each item returned from an iterator. `iter.sum(closure)` is equivalent to: `iter.collect(closure).sum()`. The iterator will become exhausted of elements after determining the sum value.

Parameters:
  `closure` - a single parameter closure that returns a numeric value..

Returns:
  The sum of the values returned by applying the closure to each item from the Iterator.

Since:
  1.7.1

### sum

    public Object sum(Object initialValue, Closure closure)

  Sums the result of applying a closure to each item of an Iterator to some initial value. `iter.sum(initVal, closure)` is equivalent to: `iter.collect(closure).sum(initVal)`. The iterator will become exhausted of elements after determining the sum value.

Parameters:
  `closure` - a single parameter closure that returns a numeric value..
  `initialValue` - the closure results will be summed to this initial value.

Returns:
  The sum of the values returned by applying the closure to each item from the Iterator.

Since:
  1.7.1

### toList

    public List toList()

  Convert an iterator to a List. The iterator will become exhausted of elements after making this conversion.

Returns:
  a List

Since:
  1.5.0

### unique

    public Iterator unique()

  Returns an iterator equivalent to this iterator all duplicated items removed by using the default comparator. The original iterator will become exhausted of elements after determining the unique values. A new iterator for the unique values will be returned.

Returns:
  the modified Iterator

Since:
  1.5.5

### unique

    public Iterator unique(Closure closure)

  Returns an iterator equivalent to this iterator but with all duplicated items removed by using a Closure to determine duplicate (equal) items. The original iterator will be fully processed after the call. If the closure takes a single parameter, the argument passed will be each element, and the closure should return a value used for comparison (either using Comparable#compareTo or Object#equals). If the closure takes two parameters, two items from the Iterator will be passed as arguments, and the closure should return an int value (with 0 indicating the items are not unique).

Parameters:
  `closure` - a Closure used to determine unique items.

Returns:
  the modified Iterator

Since:
  1.5.5

### unique

    public Iterator unique(Comparator comparator)

  Returns an iterator equivalent to this iterator with all duplicated items removed by using the supplied comparator.

Parameters:
  `comparator` - a Comparator.

Returns:
  the modified Iterator

Since:
  1.5.5

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