MergeIterator (Flink : Runtime 2.1.0 API)

java.lang.Object
- org.apache.flink.runtime.operators.sort.MergeIterator<E>

All Implemented Interfaces:

org.apache.flink.util.MutableObjectIterator<E>
```
public class MergeIterator<E>
extends Object
implements org.apache.flink.util.MutableObjectIterator<E>
```
An iterator that returns a sorted merge of the sequences of elements from a set of iterators, assuming those sequences are ordered themselves. The iterators to be merged are kept internally as a heap, making each access to the next smallest element logarithmic in complexity, with respect to the number of streams to be merged. The order among the elements is established using the methods from the TypeComparator class, specifically TypeComparator.setReference(Object) and TypeComparator.compareToReference(TypeComparator).

Constructor Summary

Constructors
Constructor	Description
`MergeIterator(List<org.apache.flink.util.MutableObjectIterator<E>> iterators, org.apache.flink.api.common.typeutils.TypeComparator<E> comparator)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`E`	`next()`	Gets the next smallest element, with respect to the definition of order implied by the `TypeSerializer` provided to this iterator.
`E`	`next(E reuse)`	Gets the next smallest element, with respect to the definition of order implied by the `TypeSerializer` provided to this iterator.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - MergeIterator
```
public MergeIterator(List<org.apache.flink.util.MutableObjectIterator<E>> iterators,
                     org.apache.flink.api.common.typeutils.TypeComparator<E> comparator)
              throws IOException
```
    Parameters:
    
    iterators -
    
    comparator -
    
    Throws:
    
    IOException
- Method Detail
  - next
```
public E next(E reuse)
       throws IOException
```
    Gets the next smallest element, with respect to the definition of order implied by the TypeSerializer provided to this iterator.
    
    Specified by:
    
    next in interface org.apache.flink.util.MutableObjectIterator<E>
    
    Parameters:
    
    reuse - Object that may be reused.
    
    Returns:
    
    The next element if the iterator has another element, null otherwise.
    
    Throws:
    
    IOException
    
    See Also:
    
    MutableObjectIterator.next(java.lang.Object)
  - next
```
public E next()
       throws IOException
```
    Gets the next smallest element, with respect to the definition of order implied by the TypeSerializer provided to this iterator.
    
    Specified by:
    
    next in interface org.apache.flink.util.MutableObjectIterator<E>
    
    Returns:
    
    The next element if the iterator has another element, null otherwise.
    
    Throws:
    
    IOException
    
    See Also:
    
    MutableObjectIterator.next()