Java 8 Resources

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Java 8 streams

A collection of 4 issues

Summary statistics on a Java 8 stream of numbers

Java 8 streams provide an easy way to calculate basic statistics on the values of a stream of numbers. We can use the summaryStatistics method to get the basic statistics: minimum, maximum, count, sum and average. List numbers = Arrays.asList(10, 3, 2, 5, 9, 4); IntSummaryStatistics stats = numbers.

Distinct elements in Java 8 streams

Finding the distinct elements of a Java stream is easy. We can use the distinct method: List words = Arrays.asList("hello", "Java8", "world!", "hello); List distinctWords = words.stream() .distinct() .collect(Collectors.toList()); // ["hello", "Java8", "world!"] The first part of the code example filters the non-empty strings and counts

Java 8 stream map

Let's map a list of words using Java 8 streams: List words = Arrays.asList("A", "bbb", "CC", "dd"); // Map the words to UPPERCASE and join them with the ":" separator String joined = words.stream() .map(String::toUpperCase) .collect(Collectors.joining(":")); // "A:BBB:CC:DD" Calling the map method of a

Filter Java 8 stream

Let's filter a list of strings using Java 8 streams: List list = Arrays.asList("a", "", "b", "", "c"); // Count the non-empty strings long nonEmptyCount = list.stream() .filter(x -> !x.isEmpty()) .count(); // 3 // Count the empty strings long emptyCount = list.stream() .filter(String::isEmpty) // same as .filter(x -> x.