Java: What is the difference between Stream.allMatch() and Stream.noneMatch()?

allMatch() — returns true if every element matches. noneMatch() — returns true if no element matches. They are logical complements — allMatch(p) is equivalent to noneMatch(p.negate()).

allMatch():

• Returns true if every element matches.
• Short-circuits on first non-match.
• Empty stream returns true (vacuously true).

1boolean allPositive = numbers.stream()
2    .allMatch(n -> n > 0);

noneMatch():

• Returns true if no element matches.
• Short-circuits on first match.
• Empty stream returns true (vacuously true).

1boolean noneNull = list.stream()
2    .noneMatch(Objects::isNull);

Relationship:

• noneMatch(p) == allMatch(p.negate())
• allMatch(p) == noneMatch(p.negate())

Empty stream:

• allMatch() → true
• noneMatch() → true

Performance considerations:

• Both are O(n) worst case, O(1) best case.
• Both short-circuit — they stop at the first decisive element.
• Choose the one that reads most naturally for your condition.

1// Check if all users are active
2boolean allActive = users.stream().allMatch(User::isActive);
3
4// Check if no orders are cancelled
5boolean noCancelled = orders.stream()
6    .noneMatch(o -> o.getStatus() == Status.CANCELLED);