Array to Set & ViceVersa...

Convert Array to a Set

Using plain Java

Let’s first look at how to convert the array to a Set using plain Java:

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@Test public void givenUsingCoreJavaV1_whenArrayConvertedToSet_thenCorrect() {     Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };     Set<Integer> targetSet = new HashSet<Integer>(Arrays.asList(sourceArray)); }

Alternatively the Set can be created first and then filled with the array elements:

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@Test public void givenUsingCoreJavaV2_whenArrayConvertedToSet_thenCorrect() {     Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };     Set<Integer> targetSet = new HashSet<Integer>();     Collections.addAll(targetSet, sourceArray); }

Convert Set to Array

Using plain Java

Now let’s look at the reverse – converting an existing Set to an array:

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@Test public void givenUsingCoreJava_whenSetConvertedToArray_thenCorrect() {     Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);     Integer[] targetArray = sourceSet.toArray(new Integer[sourceSet.size()]); }

Source: http://www.baeldung.com/convert-array-to-set-and-set-to-array