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Predicate.not() for negation

Use Predicate.not() to negate method references cleanly instead of writing lambda wrappers.

Code Comparison

✕ Java 8

List<String> nonEmpty = list.stream()
    .filter(s -> !s.isBlank())
    .collect(Collectors.toList());

✓ Java 11+

List<String> nonEmpty = list.stream()
    .filter(Predicate.not(String::isBlank))
    .collect(Collectors.toList());

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Why the modern way wins

👁

Cleaner negation

No need to wrap method references in lambdas just to negate them.

🔗

Composable

Works with any Predicate, enabling clean predicate chains.

📖

Reads naturally

Predicate.not(String::isBlank) reads like English.

Old Approach

Lambda negation

Modern Approach

Predicate.not()

Since JDK

Difficulty

Beginner

JDK Support

Predicate.not() for negation

Available

Available since JDK 11 (September 2018).

How it works

Before Java 11, negating a method reference required wrapping it in a lambda. Predicate.not() lets you negate any predicate directly, keeping the code readable and consistent with method reference style throughout the stream pipeline.

Stream.toList()

Java 8

List<String> result = stream
    .filter(s -> s.length() > 3)
    .collect(Collectors.toList());

Java 16+

List<String> result = stream
    .filter(s -> s.length() > 3)
    .toList();

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JDK 16+ →

Strings Beginner

String.isBlank()

Java 8

boolean blank =
    str.trim().isEmpty();
// or: str.trim().length() == 0

Java 11+

boolean blank = str.isBlank();
// handles Unicode whitespace too

Hover to see modern ➜

JDK 11+ →

Streams Beginner

Stream takeWhile / dropWhile

Java 8

List<Integer> result = new ArrayList<>();
for (int n : sorted) {
    if (n >= 100) break;
    result.add(n);
}
// no stream equivalent in Java 8

Java 9+

var result = sorted.stream()
    .takeWhile(n -> n < 100)
    .toList();
// or: .dropWhile(n -> n < 10)

Hover to see modern ➜

JDK 9+ →