Java: What is the difference between Stream.collect() and Stream.toArray()?

collect() — accumulates into a collection (List, Set, Map, etc.). toArray() — converts to a fixed-size array. Think of collect() as filling a flexible toolbox, while toArray() as packing items into a fixed-size crate.

collect():

• Uses a Collector.
• Returns List, Set, Map, String, etc.
• Flexible accumulation.

1List<String> list = stream.collect(Collectors.toList());
2Set<Integer> set = stream.collect(Collectors.toSet());
3Map<String, Integer> map = stream
4    .collect(Collectors.toMap(s -> s, String::length));

toArray():

• Returns Object[] or typed array.
• Fixed-size array.
• No Collector needed.

1Object[] arr = stream.toArray();
2String[] arr = stream.toArray(String[]::new);

Key difference:

• collect() — flexible, various collections.
• toArray() — fixed array result.

Performance considerations:

• toArray() is slightly faster for array creation.
• collect(toList()) is more common and flexible.
• For API boundaries that require arrays, use toArray().
• For internal processing, prefer collect(toList()) or toList().