Package org.eclipse.collections.api.stack

Interface StackIterable<T>

All Superinterfaces:
InternalIterable<T>, Iterable<T>, OrderedIterable<T>, RichIterable<T>
All Known Subinterfaces:
ImmutableStack<T>, MutableStack<T>
All Known Implementing Classes:
ArrayStack, SynchronizedStack, UnmodifiableStack
public interface StackIterable<T>
extends OrderedIterable<T>
StackIterable is a last-in-first-out data structure. All iteration methods iterate from the "top" of the stack to the "bottom". In other words, it processes the most recently added elements first.

For example:

RichIterable.forEach(Procedure) iterates over every element, starting with the most recently added

getFirst() returns the most recently added element, not the element that was added first

toString() follows the same rules as AbstractCollection.toString() except it processes the elements in the same order as forEach().

  • Method Details

    • peek

      T peek()
      Returns the element at the top of the stack, without removing it from the stack.
      Returns:
      the top of the stack.

    • peek

      ListIterable<T> peek​(int count)
      Returns:
      a ListIterable of the number of elements specified by the count, beginning with the top of the stack.

    • peekAt

      T peekAt​(int index)
      Returns the element at a specific index, without removing it from the stack.
      Parameters:
      index - the location to peek into
      Returns:
      the element at the specified index

    • getFirst

      default T getFirst()
      Should return the same value as peek().
      Specified by:
      getFirst in interface OrderedIterable<T>
      Specified by:
      getFirst in interface RichIterable<T>

    • getLast

      T getLast()
      Should not work as it violates the contract of a Stack.
      Specified by:
      getLast in interface OrderedIterable<T>
      Specified by:
      getLast in interface RichIterable<T>

    • toString

      String toString()
      Follows the same rules as AbstractCollection.toString() except it processes the elements in the same order as forEach(). 
       Assert.assertEquals("[3, 2, 1]", Stacks.mutable.with(1, 2, 3).toString());
      Specified by:
      toString in interface RichIterable<T>
      Overrides:
      toString in class Object
      Returns:
      a string representation of this RichIterable
      See Also:
      AbstractCollection.toString()

    • equals

      boolean equals​(Object o)
      Follows the same general contract as List.equals(Object), but for Stacks.
      Overrides:
      equals in class Object

    • hashCode

      int hashCode()
      Follows the same general contract as List.hashCode(), but for Stacks.
      Overrides:
      hashCode in class Object

    • takeWhile

      StackIterable<T> takeWhile​(Predicate<? super T> predicate)
      Description copied from interface: OrderedIterable
      Returns the initial elements that satisfy the Predicate. Short circuits at the first element which does not satisfy the Predicate.
      Specified by:
      takeWhile in interface OrderedIterable<T>

    • dropWhile

      StackIterable<T> dropWhile​(Predicate<? super T> predicate)
      Description copied from interface: OrderedIterable
      Returns the final elements that do not satisfy the Predicate. Short circuits at the first element which does satisfy the Predicate.
      Specified by:
      dropWhile in interface OrderedIterable<T>

    • partitionWhile

      PartitionStack<T> partitionWhile​(Predicate<? super T> predicate)
      Description copied from interface: OrderedIterable
      Returns a Partition of the initial elements that satisfy the Predicate and the remaining elements. Short circuits at the first element which does satisfy the Predicate.
      Specified by:
      partitionWhile in interface OrderedIterable<T>

    • distinct

      StackIterable<T> distinct()
      Description copied from interface: OrderedIterable
      Returns a new OrderedIterable containing the distinct elements in this iterable.

      Conceptually similar to RichIterable.toSet().RichIterable.toList() but retains the original order. If an element appears multiple times in this iterable, the first one will be copied into the result.

      Specified by:
      distinct in interface OrderedIterable<T>
      Returns:
      OrderedIterable of distinct elements

    • toStack

      default MutableStack<T> toStack()
      Converts the stack to a MutableStack implementation.
      Specified by:
      toStack in interface OrderedIterable<T>
      Since:
      2.0

    • tap

      StackIterable<T> tap​(Procedure<? super T> procedure)
      Description copied from interface: RichIterable
      Executes the Procedure for each element in the iterable and returns this.

      Example using a Java 8 lambda expression: 

       RichIterable<Person> tapped =
     people.tap(person -> LOGGER.info(person.getName()));

      Example using an anonymous inner class: 

       RichIterable<Person> tapped =
     people.tap(new Procedure<Person>()
     {
         public void value(Person person)
         {
             LOGGER.info(person.getName());
         }
     });
      Specified by:
      tap in interface OrderedIterable<T>
      Specified by:
      tap in interface RichIterable<T>
      See Also:
      RichIterable.each(Procedure), RichIterable.forEach(Procedure)

    • select

      StackIterable<T> select​(Predicate<? super T> predicate)
      Description copied from interface: RichIterable
      Returns all elements of the source collection that return true when evaluating the predicate. This method is also commonly called filter.

      Example using a Java 8 lambda expression: 

       RichIterable<Person> selected =
     people.select(person -> person.getAddress().getCity().equals("London"));

      Example using an anonymous inner class: 

       RichIterable<Person> selected =
     people.select(new Predicate<Person>()
     {
         public boolean accept(Person person)
         {
             return person.getAddress().getCity().equals("London");
         }
     });
      Specified by:
      select in interface OrderedIterable<T>
      Specified by:
      select in interface RichIterable<T>

    • selectWith

      <P> StackIterable<T> selectWith​(Predicate2<? super T,​? super P> predicate, P parameter)
      Description copied from interface: RichIterable
      Similar to RichIterable.select(Predicate), except with an evaluation parameter for the second generic argument in Predicate2.

      E.g. return a Collection of Person elements where the person has an age greater than or equal to 18 years

      Example using a Java 8 lambda expression: 

       RichIterable<Person> selected =
     people.selectWith((Person person, Integer age) -> person.getAge()>= age, Integer.valueOf(18));

      Example using an anonymous inner class: 

       RichIterable<Person> selected =
     people.selectWith(new Predicate2<Person, Integer>()
     {
         public boolean accept(Person person, Integer age)
         {
             return person.getAge()>= age;
         }
     }, Integer.valueOf(18));
      Specified by:
      selectWith in interface OrderedIterable<T>
      Specified by:
      selectWith in interface RichIterable<T>
      Parameters:
      predicate - a Predicate2 to use as the select criteria
      parameter - a parameter to pass in for evaluation of the second argument P in predicate
      See Also:
      RichIterable.select(Predicate)

    • reject

      StackIterable<T> reject​(Predicate<? super T> predicate)
      Description copied from interface: RichIterable
      Returns all elements of the source collection that return false when evaluating of the predicate. This method is also sometimes called filterNot and is the equivalent of calling iterable.select(Predicates.not(predicate)).

      Example using a Java 8 lambda expression: 

       RichIterable<Person> rejected =
     people.reject(person -> person.person.getLastName().equals("Smith"));

      Example using an anonymous inner class: 

       RichIterable<Person> rejected =
     people.reject(new Predicate<Person>()
     {
         public boolean accept(Person person)
         {
             return person.person.getLastName().equals("Smith");
         }
     });
      Specified by:
      reject in interface OrderedIterable<T>
      Specified by:
      reject in interface RichIterable<T>
      Parameters:
      predicate - a Predicate to use as the reject criteria
      Returns:
      a RichIterable that contains elements that cause Predicate.accept(Object) method to evaluate to false

    • rejectWith

      <P> StackIterable<T> rejectWith​(Predicate2<? super T,​? super P> predicate, P parameter)
      Description copied from interface: RichIterable
      Similar to RichIterable.reject(Predicate), except with an evaluation parameter for the second generic argument in Predicate2.

      E.g. return a Collection of Person elements where the person has an age greater than or equal to 18 years

      Example using a Java 8 lambda expression: 

       RichIterable<Person> rejected =
     people.rejectWith((Person person, Integer age) -> person.getAge() < age, Integer.valueOf(18));

      Example using an anonymous inner class: 

       MutableList<Person> rejected =
     people.rejectWith(new Predicate2<Person, Integer>()
     {
         public boolean accept(Person person, Integer age)
         {
             return person.getAge() < age;
         }
     }, Integer.valueOf(18));
      Specified by:
      rejectWith in interface OrderedIterable<T>
      Specified by:
      rejectWith in interface RichIterable<T>
      Parameters:
      predicate - a Predicate2 to use as the select criteria
      parameter - a parameter to pass in for evaluation of the second argument P in predicate
      See Also:
      RichIterable.select(Predicate)

    • selectInstancesOf

      <S> StackIterable<S> selectInstancesOf​(Class<S> clazz)
      Description copied from interface: RichIterable
      Returns all elements of the source collection that are instances of the Class clazz. 
       RichIterable<Integer> integers =
     List.mutable.with(new Integer(0), new Long(0L), new Double(0.0)).selectInstancesOf(Integer.class);
      Specified by:
      selectInstancesOf in interface OrderedIterable<T>
      Specified by:
      selectInstancesOf in interface RichIterable<T>

    • partition

      PartitionStack<T> partition​(Predicate<? super T> predicate)
      Description copied from interface: RichIterable
      Filters a collection into a PartitionedIterable based on the evaluation of the predicate.

      Example using a Java 8 lambda expression: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partition(person -> person.getAddress().getState().getName().equals("New York"));

      Example using an anonymous inner class: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partition(new Predicate<Person>()
     {
         public boolean accept(Person person)
         {
             return person.getAddress().getState().getName().equals("New York");
         }
     });
      Specified by:
      partition in interface OrderedIterable<T>
      Specified by:
      partition in interface RichIterable<T>

    • partitionWith

      <P> PartitionStack<T> partitionWith​(Predicate2<? super T,​? super P> predicate, P parameter)
      Description copied from interface: RichIterable
      Filters a collection into a PartitionIterable based on the evaluation of the predicate.

      Example using a Java 8 lambda expression: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partitionWith((Person person, String state) -> person.getAddress().getState().getName().equals(state), "New York");

      Example using an anonymous inner class: 

       PartitionIterable<Person> newYorkersAndNonNewYorkers =
     people.partitionWith(new Predicate2<Person, String>()
     {
         public boolean accept(Person person, String state)
         {
             return person.getAddress().getState().getName().equals(state);
         }
     }, "New York");
      Specified by:
      partitionWith in interface OrderedIterable<T>
      Specified by:
      partitionWith in interface RichIterable<T>

    • collect

      <V> StackIterable<V> collect​(Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      Returns a new collection with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       RichIterable<String> names =
     people.collect(person -> person.getFirstName() + " " + person.getLastName());

      Example using an anonymous inner class: 

       RichIterable<String> names =
     people.collect(new Function<Person, String>()
     {
         public String valueOf(Person person)
         {
             return person.getFirstName() + " " + person.getLastName();
         }
     });
      Specified by:
      collect in interface OrderedIterable<T>
      Specified by:
      collect in interface RichIterable<T>

    • collectBoolean

      BooleanStack collectBoolean​(BooleanFunction<? super T> booleanFunction)
      Description copied from interface: RichIterable
      Returns a new primitive boolean iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       BooleanIterable licenses =
     people.collectBoolean(person -> person.hasDrivingLicense());

      Example using an anonymous inner class: 

       BooleanIterable licenses =
     people.collectBoolean(new BooleanFunction<Person>()
     {
         public boolean booleanValueOf(Person person)
         {
             return person.hasDrivingLicense();
         }
     });
      Specified by:
      collectBoolean in interface OrderedIterable<T>
      Specified by:
      collectBoolean in interface RichIterable<T>

    • collectByte

      ByteStack collectByte​(ByteFunction<? super T> byteFunction)
      Description copied from interface: RichIterable
      Returns a new primitive byte iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       ByteIterable bytes =
     people.collectByte(person -> person.getCode());

      Example using an anonymous inner class: 

       ByteIterable bytes =
     people.collectByte(new ByteFunction<Person>()
     {
         public byte byteValueOf(Person person)
         {
             return person.getCode();
         }
     });
      Specified by:
      collectByte in interface OrderedIterable<T>
      Specified by:
      collectByte in interface RichIterable<T>

    • collectChar

      CharStack collectChar​(CharFunction<? super T> charFunction)
      Description copied from interface: RichIterable
      Returns a new primitive char iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       CharIterable chars =
     people.collectChar(person -> person.getMiddleInitial());

      Example using an anonymous inner class: 

       CharIterable chars =
     people.collectChar(new CharFunction<Person>()
     {
         public char charValueOf(Person person)
         {
             return person.getMiddleInitial();
         }
     });
      Specified by:
      collectChar in interface OrderedIterable<T>
      Specified by:
      collectChar in interface RichIterable<T>

    • collectDouble

      DoubleStack collectDouble​(DoubleFunction<? super T> doubleFunction)
      Description copied from interface: RichIterable
      Returns a new primitive double iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       DoubleIterable doubles =
     people.collectDouble(person -> person.getMilesFromNorthPole());

      Example using an anonymous inner class: 

       DoubleIterable doubles =
     people.collectDouble(new DoubleFunction<Person>()
     {
         public double doubleValueOf(Person person)
         {
             return person.getMilesFromNorthPole();
         }
     });
      Specified by:
      collectDouble in interface OrderedIterable<T>
      Specified by:
      collectDouble in interface RichIterable<T>

    • collectFloat

      FloatStack collectFloat​(FloatFunction<? super T> floatFunction)
      Description copied from interface: RichIterable
      Returns a new primitive float iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       FloatIterable floats =
     people.collectFloat(person -> person.getHeightInInches());

      Example using an anonymous inner class: 

       FloatIterable floats =
     people.collectFloat(new FloatFunction<Person>()
     {
         public float floatValueOf(Person person)
         {
             return person.getHeightInInches();
         }
     });
      Specified by:
      collectFloat in interface OrderedIterable<T>
      Specified by:
      collectFloat in interface RichIterable<T>

    • collectInt

      IntStack collectInt​(IntFunction<? super T> intFunction)
      Description copied from interface: RichIterable
      Returns a new primitive int iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       IntIterable ints =
     people.collectInt(person -> person.getAge());

      Example using an anonymous inner class: 

       IntIterable ints =
     people.collectInt(new IntFunction<Person>()
     {
         public int intValueOf(Person person)
         {
             return person.getAge();
         }
     });
      Specified by:
      collectInt in interface OrderedIterable<T>
      Specified by:
      collectInt in interface RichIterable<T>

    • collectLong

      LongStack collectLong​(LongFunction<? super T> longFunction)
      Description copied from interface: RichIterable
      Returns a new primitive long iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       LongIterable longs =
     people.collectLong(person -> person.getGuid());

      Example using an anonymous inner class: 

       LongIterable longs =
     people.collectLong(new LongFunction<Person>()
     {
         public long longValueOf(Person person)
         {
             return person.getGuid();
         }
     });
      Specified by:
      collectLong in interface OrderedIterable<T>
      Specified by:
      collectLong in interface RichIterable<T>

    • collectShort

      ShortStack collectShort​(ShortFunction<? super T> shortFunction)
      Description copied from interface: RichIterable
      Returns a new primitive short iterable with the results of applying the specified function on each element of the source collection. This method is also commonly called transform or map.

      Example using a Java 8 lambda expression: 

       ShortIterable shorts =
     people.collectShort(person -> person.getNumberOfJunkMailItemsReceivedPerMonth());

      Example using an anonymous inner class: 

       ShortIterable shorts =
     people.collectShort(new ShortFunction<Person>()
     {
         public short shortValueOf(Person person)
         {
             return person.getNumberOfJunkMailItemsReceivedPerMonth();
         }
     });
      Specified by:
      collectShort in interface OrderedIterable<T>
      Specified by:
      collectShort in interface RichIterable<T>

    • collectWith

      <P,​ V> StackIterable<V> collectWith​(Function2<? super T,​? super P,​? extends V> function, P parameter)
      Description copied from interface: RichIterable
      Same as RichIterable.collect(Function) with a Function2 and specified parameter which is passed to the block.

      Example using a Java 8 lambda expression: 

       RichIterable<Integer> integers =
     Lists.mutable.with(1, 2, 3).collectWith((each, parameter) -> each + parameter, Integer.valueOf(1));

      Example using an anonymous inner class: 

       Function2<Integer, Integer, Integer> addParameterFunction =
     new Function2<Integer, Integer, Integer>()
     {
         public Integer value(Integer each, Integer parameter)
         {
             return each + parameter;
         }
     };
 RichIterable<Integer> integers =
     Lists.mutable.with(1, 2, 3).collectWith(addParameterFunction, Integer.valueOf(1));
      Specified by:
      collectWith in interface OrderedIterable<T>
      Specified by:
      collectWith in interface RichIterable<T>
      Parameters:
      function - A Function2 to use as the collect transformation function
      parameter - A parameter to pass in for evaluation of the second argument P in function
      Returns:
      A new RichIterable that contains the transformed elements returned by Function2.value(Object, Object)
      See Also:
      RichIterable.collect(Function)

    • collectIf

      <V> StackIterable<V> collectIf​(Predicate<? super T> predicate, Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      Returns a new collection with the results of applying the specified function on each element of the source collection, but only for those elements which return true upon evaluation of the predicate. This is the the optimized equivalent of calling iterable.select(predicate).collect(function).

      Example using a Java 8 lambda and method reference: 

       RichIterable<String> strings = Lists.mutable.with(1, 2, 3).collectIf(e -> e != null, Object::toString);

      Example using Predicates factory: 

       RichIterable<String> strings = Lists.mutable.with(1, 2, 3).collectIf(Predicates.notNull(), Functions.getToString());
      Specified by:
      collectIf in interface OrderedIterable<T>
      Specified by:
      collectIf in interface RichIterable<T>

    • collectWithIndex

      default <V> StackIterable<V> collectWithIndex​(ObjectIntToObjectFunction<? super T,​? extends V> function)
      Description copied from interface: OrderedIterable
      Returns a new OrderedIterable using results obtained by applying the specified function to each element and its corresponding index.
      Specified by:
      collectWithIndex in interface OrderedIterable<T>
      Since:
      9.1.

    • flatCollect

      <V> StackIterable<V> flatCollect​(Function<? super T,​? extends Iterable<V>> function)
      Description copied from interface: RichIterable
      flatCollect is a special case of RichIterable.collect(Function). With collect, when the Function returns a collection, the result is a collection of collections. flatCollect outputs a single "flattened" collection instead. This method is commonly called flatMap.

      Consider the following example where we have a Person class, and each Person has a list of Address objects. Take the following Function: 

       Function<Person, List<Address>> addressFunction = Person::getAddresses;
 RichIterable<Person> people = ...;
      Using collect returns a collection of collections of addresses. 
       RichIterable<List<Address>> addresses = people.collect(addressFunction);
      Using flatCollect returns a single flattened list of addresses. 
       RichIterable<Address> addresses = people.flatCollect(addressFunction);
      Specified by:
      flatCollect in interface OrderedIterable<T>
      Specified by:
      flatCollect in interface RichIterable<T>
      Parameters:
      function - The Function to apply
      Returns:
      a new flattened collection produced by applying the given function

    • flatCollectWith

      default <P,​ V> StackIterable<V> flatCollectWith​(Function2<? super T,​? super P,​? extends Iterable<V>> function, P parameter)
      Specified by:
      flatCollectWith in interface OrderedIterable<T>
      Specified by:
      flatCollectWith in interface RichIterable<T>
      Since:
      9.2

    • groupBy

      <V> ListMultimap<V,​T> groupBy​(Function<? super T,​? extends V> function)
      Description copied from interface: RichIterable
      For each element of the iterable, the function is evaluated and the results of these evaluations are collected into a new multimap, where the transformed value is the key and the original values are added to the same (or similar) species of collection as the source iterable.

      Example using a Java 8 method reference: 

       Multimap<String, Person> peopleByLastName =
     people.groupBy(Person::getLastName);

      Example using an anonymous inner class: 

       Multimap<String, Person> peopleByLastName =
     people.groupBy(new Function<Person, String>()
     {
         public String valueOf(Person person)
         {
             return person.getLastName();
         }
     });
      Specified by:
      groupBy in interface OrderedIterable<T>
      Specified by:
      groupBy in interface RichIterable<T>

    • groupByEach

      <V> ListMultimap<V,​T> groupByEach​(Function<? super T,​? extends Iterable<V>> function)
      Description copied from interface: RichIterable
      Similar to RichIterable.groupBy(Function), except the result of evaluating function will return a collection of keys for each value.
      Specified by:
      groupByEach in interface OrderedIterable<T>
      Specified by:
      groupByEach in interface RichIterable<T>

    • zip

      <S> StackIterable<Pair<T,​S>> zip​(Iterable<S> that)
      Description copied from interface: OrderedIterable
      Returns a OrderedIterable formed from this OrderedIterable and another Iterable by combining corresponding elements in pairs. The second Iterable should also be ordered. If one of the two Iterables is longer than the other, its remaining elements are ignored.
      Specified by:
      zip in interface OrderedIterable<T>
      Specified by:
      zip in interface RichIterable<T>
      Type Parameters:
      S - the type of the second half of the returned pairs
      Parameters:
      that - The Iterable providing the second half of each result pair
      Returns:
      A new OrderedIterable containing pairs consisting of corresponding elements of this OrderedIterable and that. The length of the returned OrderedIterable is the minimum of the lengths of this OrderedIterable and that.

    • zipWithIndex

      StackIterable<Pair<T,​Integer>> zipWithIndex()
      Description copied from interface: RichIterable
      Zips this RichIterable with its indices.
      Specified by:
      zipWithIndex in interface OrderedIterable<T>
      Specified by:
      zipWithIndex in interface RichIterable<T>
      Returns:
      A new RichIterable containing pairs consisting of all elements of this RichIterable paired with their index. Indices start at 0.
      See Also:
      RichIterable.zip(Iterable)

    • toImmutable

      ImmutableStack<T> toImmutable()
      Converts the StackIterable to an immutable implementation. Returns this for immutable stacks.
      Since:
      5.0