How to convert a Collection to List?

Checking before conversion

There might be special occasions when your collection is already a List. Gently ask it with instanceof to check:

if (yourCollection instanceof List) {
    // imagine our surprise
    // "Hey, bro, you're already a List, what's with the identity crisis?"
    List<String> list = (List<String>) yourCollection;
} else {
    List<String> list = new ArrayList<>(yourCollection);
}
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Converting needlessly is like reinventing the wheel, so to avoid redundancy, check first!

Advanced conversion strategies

Stream party with modern Java

Java 8 and beyond have a cool party trick called Stream API. It helps you convert collections to lists in a more funky style:

List<String> list = yourCollection.stream().collect(Collectors.toList());
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For parallel processing, turn that single lane .stream() into a freeway .parallelStream(). With large collections, this is as good as it gets.

What's new in Java 10?

List<String> list = List.copyOf(yourCollection);
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From Java 10 onward, the List.copyOf() method makes a sense for Jim Carrey fans, as it returns an unmodifiable List. It's perfect when your data should be as unchanging as the character Stanley Ipkiss from "The Mask".

Time to sort

Meet Mr. Collections.sort()

Once you pull out a List, you might get the sudden urge to sort it:

Collections.sort(list);
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Without any manager, it arranges your data in its natural order. But wait, there's a catch! If you're into custom sorting, it also accepts a Comparator:

// String play in a few lines
// Organizing by length because 'why not?'
Collections.sort(list, Comparator.comparing(String::length));
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A TreeBidiMap Love Story

Need to get values out of a TreeBidiMap? Use this approach to manipulate your data more efficiently:

List<Double> valuesList = new ArrayList<>(themap.values());
Collections.sort(valuesList);
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Remember, once you sort the values, call up themap.getKey(). It's like matching lost keys and forgotten values, Sherlock Holmes style!

Handling performance

Beware of large collections

While converting a Collection to a List, mind the performance. Like a sports car, this process is easy, but the engine can overheat with large collections. To cool it down, think about lazy loading or streaming data.

synchronized List

If thread safety is required, use Vector or Collections.synchronizedList(). Like a traffic cop in busy traffic, they manage your threads in a synchronized fashion.

Preserving ordering logic

When dealing with a Map or a TreeBidiMap, ensure that your sorted order retains the intended logic. It's crucial if you have potential keys to reclaim and a vault of values to unlock.

Trust the Javamasters

Your best ally is Java's built-in features. They are reliable soldiers, thoroughly tested and well-trained, ready for any combat scenario.