Class PushbackIterator<E>
java.lang.Object
org.apache.commons.collections4.iterators.PushbackIterator<E>
- All Implemented Interfaces:
Iterator<E>
Decorates an iterator to support pushback of elements.
The decorator stores the pushed back elements in a LIFO manner: the last element
that has been pushed back, will be returned as the next element in a call to next()
.
The decorator does not support the removal operation. Any call to remove()
will
result in an UnsupportedOperationException
.
- Since:
- 4.0
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionboolean
hasNext()
next()
void
Push back the given element to the iterator.static <E> PushbackIterator<E>
pushbackIterator
(Iterator<? extends E> iterator) Decorates the specified iterator to support one-element lookahead.void
remove()
This iterator will always throw anUnsupportedOperationException
.
-
Constructor Details
-
PushbackIterator
Constructor.- Parameters:
iterator
- the iterator to decorate
-
-
Method Details
-
pushbackIterator
Decorates the specified iterator to support one-element lookahead.If the iterator is already a
PushbackIterator
it is returned directly.- Type Parameters:
E
- the element type- Parameters:
iterator
- the iterator to decorate- Returns:
- a new peeking iterator
- Throws:
NullPointerException
- if the iterator is null
-
pushback
Push back the given element to the iterator.Calling
next()
immediately afterwards will return exactly this element.- Parameters:
item
- the element to push back to the iterator
-
hasNext
-
next
-
remove
This iterator will always throw anUnsupportedOperationException
.- Specified by:
remove
in interfaceIterator<E>
- Throws:
UnsupportedOperationException
- always
-