Most concise way to convert a Set<T> to a List<T>

Diving into alternatives and noted practices

The single-liner above is certainly eye-catching. But there's always room for enhancement. Let's tackle different methods, subtle aspects, and best practices to convert a Set into a List in Java.

Different libraries, different strokes

If Guava is your partner in crime, accomplish the same with:

// Remember, 'Objects.firstNonNull()` is your safety net while tight roping with nulls.
import com.google.common.collect.Lists;

List<T> myList = Lists.newArrayList(mySet);
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Seeking immortality? Java 10's List.copyOf provides an unmodifiable list:

// Motto of the masochistic Java developer - "Thou shall not modify!"
List<T> immortalList = List.copyOf(mySet);
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For those living in the past, Collections.unmodifiableList from ancient Java versions will do:

// Being immutable in mutable world is a fun challenge.
List<T> immortalList = Collections.unmodifiableList(new ArrayList<>(mySet));
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Flexing Java Streams

For ensuring List type control or executing mid-conversion transformations, Java Streams is your muscle-man:

// Walmart of Java—you want it, Stream's got it.
List<T> myList = mySet.stream()
    .collect(Collectors.toCollection(ArrayList::new));
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For an immutable list via streams, use collectingAndThen with Collectors.toUnmodifiableList:

// Creating an Immutable List via Streams is as easy as ordering a pizza.
List<T> myList = mySet.stream()
    .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
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Performance considerations and large sets

For larger-than-life sets, converting to an array before to a list (e.g., Arrays.asList(set.toArray(new T[0]))) can cause performance drama and type safety crisis with generics. My advice? Use the ArrayList constructor directly. Saves time, saves face!

Pick your battles wisely

If you're dealing with specific List implementations, pay attention to key characteristics: synchronized access or constant-time positional access. Variety is the spice of conversion:

• ArrayList: Jack of all trades, master of... well, most!
• LinkedList: Comes to rescue when there's a lot of add/remove action happening.

Weigh your options based on your needs and battle accordingly.

Crossroads of thread safety and interoperability

In scenarios with multiple threads running amuck, consider the revered synchronized wrappers or the humbler concurrent collections:

// Synchronized list – making threads march to the same beat.
List<T> synchronizedList = Collections.synchronizedList(new ArrayList<>(mySet));
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For legacy code compatibility where Vector or Stack stand their ground, adapt the collection. Old is not always gold, but sometimes it's necessary.