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java.lang.Objectorg.apache.commons.collections.iterators.ReverseListIterator
public class ReverseListIterator
Iterates backwards through a List, starting with the last element and continuing to the first. This is useful for looping around a list in reverse order without needing to actually reverse the list.
The first call to next()
will return the last element
from the list, and so on. The hasNext()
method works
in concert with the next()
method as expected.
However, the nextIndex()
method returns the correct
index in the list, thus it starts high and reduces as the iteration
continues. The previous methods work similarly.
Constructor Summary | |
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ReverseListIterator(List list)
Constructor that wraps a list. |
Method Summary | |
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void |
add(Object obj)
Adds a new element to the list between the next and previous elements. |
boolean |
hasNext()
Checks whether there is another element. |
boolean |
hasPrevious()
Checks whether there is a previous element. |
Object |
next()
Gets the next element. |
int |
nextIndex()
Gets the index of the next element. |
Object |
previous()
Gets the previous element. |
int |
previousIndex()
Gets the index of the previous element. |
void |
remove()
Removes the last returned element. |
void |
reset()
Resets the iterator back to the start (which is the end of the list as this is a reversed iterator) |
void |
set(Object obj)
Replaces the last returned element. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public ReverseListIterator(List list)
list
- the list to create a reversed iterator for
NullPointerException
- if the list is nullMethod Detail |
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public boolean hasNext()
hasNext
in interface Iterator
hasNext
in interface ListIterator
public Object next()
next
in interface Iterator
next
in interface ListIterator
public int nextIndex()
nextIndex
in interface ListIterator
public boolean hasPrevious()
hasPrevious
in interface ListIterator
public Object previous()
previous
in interface ListIterator
public int previousIndex()
previousIndex
in interface ListIterator
public void remove()
remove
in interface Iterator
remove
in interface ListIterator
UnsupportedOperationException
- if the list is unmodifiable
IllegalStateException
- if there is no element to removepublic void set(Object obj)
set
in interface ListIterator
obj
- the object to set
UnsupportedOperationException
- if the list is unmodifiable
IllegalStateException
- if the iterator is not in a valid state for setpublic void add(Object obj)
add
in interface ListIterator
obj
- the object to add
UnsupportedOperationException
- if the list is unmodifiable
IllegalStateException
- if the iterator is not in a valid state for setpublic void reset()
reset
in interface ResettableIterator
reset
in interface ResettableListIterator
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