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    copied!<p>Try something like this:</p> <pre><code>public static void generate(int[][] sets) { int solutions = 1; for(int i = 0; i &lt; sets.length; solutions *= sets[i].length, i++); for(int i = 0; i &lt; solutions; i++) { int j = 1; for(int[] set : sets) { System.out.print(set[(i/j)%set.length] + " "); j *= set.length; } System.out.println(); } } public static void main(String[] args) { generate(new int[][]{{1,2,3}, {3,2}, {5,6,7}}); } </code></pre> <p>which will print:</p> <pre><code>1 3 5 2 3 5 3 3 5 1 2 5 2 2 5 3 2 5 1 3 6 2 3 6 3 3 6 1 2 6 2 2 6 3 2 6 1 3 7 2 3 7 3 3 7 1 2 7 2 2 7 3 2 7 </code></pre> <p>I've implemented the algorithm above based on (I believe) one of Knuth's <a href="http://www-cs-staff.stanford.edu/~uno/taocp.html" rel="nofollow noreferrer">TAOCP</a> books (in the comments @chikitin has a more specific reference: it is in PRE FASCICLE 2A section 7.2.1.1 Generating All n-tuple, of The Art Of Computer Programming by Knuth, Addison Wesley).</p> <p>Note that I've named the arrays <code>set</code>, but they needn't hold unique elements, of course. The time I used it, they did contain unique elements, hence the name.</p> <h2>EDIT</h2> <p>It's pretty much a 1-on-1 translation:</p> <pre><code>import java.util.Arrays; import java.util.LinkedHashMap; import java.util.Vector; public class Foo { private LinkedHashMap&lt;String, Vector&lt;String&gt;&gt; dataStructure; public Foo(LinkedHashMap&lt;String, Vector&lt;String&gt;&gt; dataStructure){ this.dataStructure = dataStructure; } public String[][] allUniqueCombinations(){ int n = dataStructure.keySet().size(); int solutions = 1; for(Vector&lt;String&gt; vector : dataStructure.values()) { solutions *= vector.size(); } String[][] allCombinations = new String[solutions + 1][]; allCombinations[0] = dataStructure.keySet().toArray(new String[n]); for(int i = 0; i &lt; solutions; i++) { Vector&lt;String&gt; combination = new Vector&lt;String&gt;(n); int j = 1; for(Vector&lt;String&gt; vec : dataStructure.values()) { combination.add(vec.get((i/j)%vec.size())); j *= vec.size(); } allCombinations[i + 1] = combination.toArray(new String[n]); } return allCombinations; } public static void main(String[] args) { LinkedHashMap&lt;String, Vector&lt;String&gt;&gt; data = new LinkedHashMap&lt;String, Vector&lt;String&gt;&gt;(); data.put("foo", new Vector&lt;String&gt;(Arrays.asList("1", "2", "3"))); data.put("bar", new Vector&lt;String&gt;(Arrays.asList("3", "2"))); data.put("baz", new Vector&lt;String&gt;(Arrays.asList("5", "6", "7"))); Foo foo = new Foo(data); for(String[] combination : foo.allUniqueCombinations()) { System.out.println(Arrays.toString(combination)); } } } </code></pre> <p>If you run the class above, the following is printed:</p> <pre><code>[foo, bar, baz] [1, 3, 5] [2, 3, 5] [3, 3, 5] [1, 2, 5] [2, 2, 5] [3, 2, 5] [1, 3, 6] [2, 3, 6] [3, 3, 6] [1, 2, 6] [2, 2, 6] [3, 2, 6] [1, 3, 7] [2, 3, 7] [3, 3, 7] [1, 2, 7] [2, 2, 7] [3, 2, 7] </code></pre>
 

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