Recipe 0.4. Generating t-uples.

You want to generate all possible t-uples.

MixedRadixNtupleFactory may generate all t-uples given the number of digits and a unique radix (same radix for each digit):

import import org.apache.commons.collections15.Transformer;

// build the factory
MixedRadixNtupleFactory factory =
	MixedRadixNtupleFactory.newInstance();

// generate all the triplets in radix 2
List<int[]> ntuples = factory.transform(3, 2);
	
// Display n-tuples
System.out.println(MixedRadixNtupleFactory.toString(ntuples));
		
// Output
//----------------------------------------------------------
// [[0, 0, 0], [0, 0, 1], [0, 1, 0], [0, 1, 1],
//  [1, 0, 0], [1, 0, 1], [1, 1, 0], [1, 1, 1],
 
Assert.assertEquals((int) Math.pow(2, 3), ntuples.size());

MixedRadixNtupleFactory can also generate all t-uples given a mixed of radices and the number of digits (different radix for each digit):

// you have to define radix for all digits
int[] radices = new int[] {3, 2, 2};
	
// generate the ntuples given the radices
List<int[]> ntuples = factory.transform(radices);
	
// Display n-tuples
System.out.println(MixedRadixNtupleFactory.toString(ntuples));
	
// Output
//----------------------------------------------------------
// [[0, 0, 0], [0, 0, 1], [0, 1, 0], [0, 1, 1],
//  [1, 0, 0], [1, 0, 1], [1, 1, 0], [1, 1, 1],
//  [2, 0, 0], [2, 0, 1], [2, 1, 0], [2, 1, 1]]

There are also many factory methods to convert t-uple to decimal and the reverse operation (see the API of MixedRadixNtupleFactory).