Introduction:

Converting a Set to a LinkedList is a common requirement in Java programming when we need to preserve the order of elements and allow duplicate values. While the Set interface provides unique and unordered elements, LinkedList offers ordered elements with the ability to store duplicates. In this blog, we will explore effective techniques to convert a Set to LinkedList in Java, discussing various methods along with their implementation, outputs, and explanations.

Method 1: Using the LinkedList Constructor

The simplest way to convert a Set to a LinkedList is by utilizing the LinkedList class's constructor. Here's the code:

Set<Integer> set = new HashSet<>(Arrays.asList(1, 2, 3, 3, 4, 5));
LinkedList<Integer> linkedList = new LinkedList<>(set);

Output:

LinkedList: [1, 2, 3, 4, 5]

In this method, we first create a Set using a HashSet and populate it with some elements, including duplicates. Then, we pass this Set as an argument to the LinkedList constructor, which initializes the LinkedList with the elements of the Set. The order is maintained, and duplicates are preserved.

Method 2: Iterating and Adding Elements

Another approach involves iterating over the Set and adding each element to the LinkedList individually. Here's an example:

Set<String> set = new HashSet<>(Arrays.asList("apple", "banana", "cherry"));
LinkedList<String> linkedList = new LinkedList<>();

for (String element : set) {
    linkedList.add(element);
}

Output:

LinkedList: [apple, banana, cherry]

In this method, we create an empty LinkedList and iterate over the Set using a for-each loop. During each iteration, we add the current element to the LinkedList using the add() method. This way, the order of elements is preserved as we traverse the Set.

Method 3: Java Streams and Collectors.toList()

Java Streams provide a concise and efficient way to convert a Set to LinkedList. We can use the stream() method to obtain a stream of elements from the Set and then collect them using the Collectors.toList() method. Here's the code:

Set<Double> set = new HashSet<>(Arrays.asList(1.2, 2.3, 3.4, 4.5));
LinkedList<Double> linkedList = set.stream()
                                   .collect(Collectors.toCollection(LinkedList::new));

Output:

LinkedList: [1.2, 2.3, 3.4, 4.5]

In this method, we create a Set and populate it with some elements. Then, we convert the Set to a stream using the stream() method. We utilize the Collectors.toCollection() method to collect the stream elements into a LinkedList. The LinkedList::new constructor reference is passed to create a new LinkedList instance.

Conclusion:

Converting a Set to a LinkedList in Java is straightforward and can be accomplished using various techniques. In this blog, we explored three effective methods: using the LinkedList constructor, iterating and adding elements, and utilizing Java Streams with Collectors.toList().