Best way to convert an ArrayList to a string

java

performance

best-practices

string-manipulation

byAnton Shumikhin·Sep 25, 2024

Instantly transform an ArrayList to a String using the Java Streams API with this code:

String result = list.stream().map(Object::toString).collect(Collectors.joining(", "));

Here, a stream is built upon your list items, each item is mapped to its String representation, and collected into one string using joining. It's direct, efficient, and keeps everything in order.

Crafting Strings with Performance in Mind

You're not just creating strings here, you're crafting them with the best performance. Consider these when handling massive ArrayLists.

StringBuilder: The Heavy Duty Option

Don't you just miss the good old days before Java 8? Well, here's how you did it with StringBuilder, especially handy for those heavier tasks.

StringBuilder sb = new StringBuilder();
for (String s : list) {
    sb.append(s).append(", ");
}
String result = sb.toString().replaceAll(", $", "");

You need one StringBuilder here; no more, no less! The StringBuilder.append operation is your best friend, so don't bring garbage and overhead into this friendship with unnecessary object creation.

Android Development Considerations

Android developers, we haven't forgotten you! The TextUtils.join method is your fiesta, providing both simplicity and a huge compatibility advantage:

String result = TextUtils.join(", ", list);

Diving into Specialized Libraries

StringUtils in Apache Commons Lang: When You Need More Power

Blog-standard join got you down? Well, consider StringUtils.join from Apache Commons Lang:

String result = StringUtils.join(list, ", ");

And if you're dealing with tab-separated values (don't ask why), use:

String result = StringUtils.join(list, "\t");

Apache Commons tackles string manipulations like a champ, providing superior performance and reliability.

Google's Guava: Software Artistry

For the lovers of the finer things in software, Google's Guava library offers Joiner:

String result = Joiner.on(", ").join(list);

And it shines particularly well in doing tab-separated strings:

String result = Joiner.on("\t").join(list);

Guava is not just about performance, it's about turning your code into a masterpiece of efficiency and elegance.

Reflecting on Performance and Practices

Performance Considerations

Ever wondered what your code looks like in the matrix...ahem, bytecode?

Placing StringBuilder outside loops can save instantiation overhead.
Optimize your loops and string operations, your bytecode self will thank you.

Cross-Platform Flexibility: One Size Does Not Fit All

When you code for multiple platforms, stay updated with the most efficient techniques out there. Speaking of which, that one size thing applies to t-shirts as well.

explain-codes / Java / Best way to convert an ArrayList to a string

Linked

How to convert a String into an ArrayList?



How to convert a char to a String?



Create a string with n characters



When to use StringBuilder in Java



How can I convert String[] to ArrayList

