How Can I Get All Maximum Values from a Java Stream?

Maximizing All Values in a Java Stream

Problem:
Java's max function in lambda expressions and streams typically returns an arbitrary element when multiple candidates tie for the maximum value. This can be undesirable when the desired behavior is to return all maximum values.

Solution:

There is currently no direct way to achieve this behavior without explicitly collecting partial results in a collection. Here are two possible approaches:

Two-Pass Approach (Collection):

1. Determine the maximum value using mapToInt(String::length).max().
2. Filter the input stream to obtain all elements that match the maximum length.

Collector-Based Approach (Single Pass):

1. Create a custom collector using the maxList method:

   static <T> Collector<T, ?, List<T>> maxList(Comparator<? super T> comp) {
    // Implementation given in the reference answer
   }

2. Use the collector to gather all elements with the maximum value in a single pass.

Example:

Using the collector-based approach:

Stream<String> input = ... ;

List<String> result = input.collect(maxList(comparing(String::length)));

This will return a list containing all strings with the maximum length in the input stream.

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