Class EmptyIterator<E>
java.lang.Object
org.apache.commons.collections4.iterators.EmptyIterator<E>
- Type Parameters:
E- the type of elements returned by this iterator.
- All Implemented Interfaces:
Iterator<E>,ResettableIterator<E>
Provides an implementation of an empty iterator.
This class provides an implementation of an empty iterator.
This class provides for binary compatibility between Commons Collections
2.1.1 and 3.1 due to issues with IteratorUtils.
- Since:
- 2.1.1 and 3.1
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final IteratorSingleton instance of the iterator.static final ResettableIteratorSingleton instance of the iterator. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoidDeprecated.Will be removed in 5.0 without replacement.static <E> Iterator<E> Gets a typed empty iterator instance.booleanhasNext()Always returns false, this iterator contains no elements.booleanAlways returns false, this iterator contains no elements.next()Always throws IllegalStateException, this iterator contains no elements.intAlways returns 0, this iterator contains no elements.previous()Always throws IllegalStateException, this iterator contains no elements.intAlways returns -1, this iterator contains no elements.voidremove()Always throws IllegalStateException, this iterator contains no elements.voidreset()Resets the iterator back to the position at which the iterator was created.static <E> ResettableIterator<E> Gets a typed resettable empty iterator instance.voidAlways throws IllegalStateException, this iterator contains no elements.Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitMethods inherited from interface java.util.Iterator
forEachRemaining
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Field Details
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RESETTABLE_INSTANCE
Singleton instance of the iterator.- Since:
- 3.1
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INSTANCE
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Constructor Details
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EmptyIterator
protected EmptyIterator()Constructs a new instance.
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Method Details
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emptyIterator
Gets a typed empty iterator instance.- Type Parameters:
E- the element type- Returns:
- Iterator<E>
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resettableEmptyIterator
Gets a typed resettable empty iterator instance.- Type Parameters:
E- the element type- Returns:
- ResettableIterator<E>
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add
Deprecated.Will be removed in 5.0 without replacement.Always throws UnsupportedOperationException.- Parameters:
ignored- ignore.- Throws:
UnsupportedOperationException- Always thrown.
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hasNext
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hasPrevious
public boolean hasPrevious()Always returns false, this iterator contains no elements.- Returns:
- Always false.
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next
Always throws IllegalStateException, this iterator contains no elements.- Specified by:
nextin interfaceIterator<E>- Returns:
- Always throws IllegalStateException.
- Throws:
IllegalStateException- Always thrown.
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nextIndex
public int nextIndex()Always returns 0, this iterator contains no elements.- Returns:
- Always returns 0.
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previous
Always throws IllegalStateException, this iterator contains no elements.- Returns:
- Always throws IllegalStateException.
- Throws:
IllegalStateException- Always thrown.
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previousIndex
public int previousIndex()Always returns -1, this iterator contains no elements.- Returns:
- Always returns -1.
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remove
public void remove()Always throws IllegalStateException, this iterator contains no elements.- Specified by:
removein interfaceIterator<E>- Throws:
IllegalStateException- Always thrown.
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reset
public void reset()Description copied from interface:ResettableIteratorResets the iterator back to the position at which the iterator was created.- Specified by:
resetin interfaceResettableIterator<E>
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set
Always throws IllegalStateException, this iterator contains no elements.- Parameters:
ignored- ignored.- Throws:
IllegalStateException- Always thrown.
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