Created
June 29, 2025 02:17
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Code snippet from The Coding Café - for.java
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public static <T, R extends Comparable<R>> Gatherer<T, ?, T> | |
takeWhileIncreasing(Function<T, R> valueExtractor) { | |
return Gatherer.of( | |
() -> new Object() { R lastValue = null; }, // 1️⃣ Anonymous class for state | |
(state, element, downstream) -> { | |
R value = valueExtractor.apply(element); // 2️⃣ Extract comparable value | |
if (state.lastValue == null || // 3️⃣ First element OR | |
value.compareTo(state.lastValue) > 0) { // value is increasing | |
state.lastValue = value; // 4️⃣ Update state | |
return downstream.push(element); // 5️⃣ Pass element along | |
} | |
return false; // 6️⃣ Stop gathering - sequence broken! | |
} | |
); | |
} | |
List<String> increasingLength = words.stream() | |
.gather(takeWhileIncreasing(String::length)) | |
.toList(); | |
System.out.println("Increasing length sequence: " + increasingLength); | |
// Output: [hello] | |
// Why? "hello"(5) → "world"(5) - not increasing, so we stop! |
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