Stream Practice: String & Character

Build a character frequency map using groupingBy with LinkedHashMap to preserve insertion order, then filter entries with count equal to 1 and findFirst.

Build a frequency map with LinkedHashMap for stable ordering, sort entries by count descending, then skip(n-1) and findFirst to get the Nth most frequent character.

Use the same LinkedHashMap frequency pattern as first non-repeating character, but on strings: groupingBy(identity(), LinkedHashMap::new, counting()), filter count equal to 1, findFirst.

Split the sentence by whitespace, normalize to lowercase, apply distinct() for alphabetical unique words, or collect to LinkedHashSet for first-occurrence order.

Use groupingBy(Function.identity(), Collectors.counting()) to produce a Map<String, Long> with the frequency of each string in the list.

`flatMap` the split words into one stream, then `distinct()` to keep each word once.

Count each character's occurrences with groupingBy and counting, then max(comparingByValue()) finds the most frequent.

new StringBuilder(s).reverse().toString() reverses a string efficiently, and a stream-based variant collects characters into a StringBuilder before reversing.

IntStream.range(0, n/2).allMatch(i -> s.charAt(i) == s.charAt(n-1-i)) checks whether a string is a palindrome by comparing each character with its mirror.

Count characters into a LinkedHashMap, filter to count == 1, then skip(1).findFirst() to get the second non-repeating character.

Convert each integer to its string form with String.valueOf, then filter by startsWith(digit) to keep numbers whose decimal representation begins with the given digit.