Java: What is the difference between Stream.findFirst() and Stream.min()?

findFirst() — returns the first element by encounter order. min() — returns the minimum element by Comparator. Think of findFirst() as the person at the front of the line (position-based), while min() as the smallest person in the group (value-based).

findFirst():

• Returns Optional<T>.
• Uses encounter order (position-based).
• First element, not necessarily smallest.

1Optional<Integer> first = list.stream()
2    .findFirst();
3// Returns first element, e.g., 5 from [5, 3, 1, 4]

min():

• Returns Optional<T>.
• Uses Comparator (value-based).
• Smallest element.

1Optional<Integer> min = list.stream()
2    .min(Integer::compareTo);
3// Returns smallest element, e.g., 1 from [5, 3, 1, 4]

Key difference:

• findFirst() — position-based (first in stream).
• min() — value-based (smallest by comparison).

1// findFirst() returns the first matching element
2Optional<String> first = list.stream()
3    .filter(s -> s.length() > 3)
4    .findFirst();
5
6// min() returns the shortest string matching
7Optional<String> shortest = list.stream()
8    .filter(s -> s.length() > 3)
9    .min(Comparator.comparing(String::length));