CartesianProductIterator

java.lang.Object
- org.apache.commons.collections4.iterators.CartesianProductIterator<E>

Type Parameters:

E - the type of the objects being permuted

All Implemented Interfaces:

java.util.Iterator<java.util.List<E>>
```
public class CartesianProductIterator<E>
extends java.lang.Object
implements java.util.Iterator<java.util.List<E>>
```
This iterator creates a Cartesian product of the input iterables, equivalent to nested for-loops.
The iterables provided to the constructor are used in reverse order, each until exhaustion before proceeding to the next element of the prior iterable and repeating. Consider the following example:
```
 List<Character> iterable1 = Arrays.asList('A', 'B', 'C');
 List<Character> iterable2 = Arrays.asList('1', '2', '3');
 CartesianProductIterator<Character> it = new CartesianProductIterator<>(
         iterable1,
         iterable2);
 while (it.hasNext()) {
     List<Character> tuple = it.next();
     System.out.println(tuple.get(0) + ", " + tuple.get(1));
 }
 
```
The output will be:
```
 A, 1
 A, 2
 A, 3
 B, 1
 B, 2
 B, 3
 C, 1
 C, 2
 C, 3
 
```
The remove() operation is not supported, and will throw an UnsupportedOperationException.

If any of the input iterables is empty, the Cartesian product will be empty. If any of the input iterables is infinite, the Cartesian product will be infinite.
Since:

4.5.0-M3

Constructor Summary

Constructors
Constructor Description

CartesianProductIterator(java.lang.Iterable<? extends E>... iterables)
Constructs a new CartesianProductIterator instance with given iterables.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`hasNext()`	Returns `true` if the iteration has more elements.
`java.util.List<E>`	`next()`	Returns the next tuple of the input iterables.
`void`	`remove()`

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

Methods inherited from interface java.util.Iterator
forEachRemaining

- Constructor Detail
  - CartesianProductIterator
```
@SafeVarargs
public CartesianProductIterator(java.lang.Iterable<? extends E>... iterables)
```
    Constructs a new CartesianProductIterator instance with given iterables.
    
    Parameters:
    
    iterables - the iterables to create the Cartesian product from
    
    Throws:
    
    java.lang.NullPointerException - if any of the iterables is null
- Method Detail
  - hasNext
```
public boolean hasNext()
```
    Returns true if the iteration has more elements.
    
    Specified by:
    
    hasNext in interface java.util.Iterator<E>
    
    Returns:
    
    true if there are more tuples, otherwise false
  - next
```
public java.util.List<E> next()
```
    Returns the next tuple of the input iterables.
    
    Specified by:
    
    next in interface java.util.Iterator<E>
    
    Returns:
    
    a list of the input iterables' elements
    
    Throws:
    
    java.util.NoSuchElementException - if there are no more tuples
  - remove
```
public void remove()
```
    Specified by:
    
    remove in interface java.util.Iterator<E>