Functional

Java Functional API

list.replaceAll(*lambda*) -- calls the lambda once for each item in the list, storing the result back into the list (or other type of collection).e.g. nums.replaceAll(n -> n * 2);

list.removeIf(*lambda*) -- calls the lambda once for each item in the collection, removing each item where the lambda returns true.e.g. nums.removeIf(n -> n < 0);

Simple Lambda Examples -- the data types are inferred from the context and from the type of the expression following the "->":n -> n * 2 -- takes Integer, returns Integern -> n < 0 && n >= -10 -- takes Integer, returns booleans -> s.length() -- takes String, returns Integers -> s.startsWith("hi") -- takes String, returns boolean

The Java stream system provides more complicated lambda features. The stream calls do not modify the original list, returning a new data structure of the results. Note that the boolean logic of filter() is the opposite of removeIf().

  List<Integer> nums = -something-;
  nums = nums.stream()
    .map(n -> n * 2)
    .filter(n -> n >= 0)
    .collect(Collectors.toList());

The above are just the most common calls, for more information see the official Java Stream Docs

Ref

• https://codingbat.com/doc/java-functional-mapping.html

• https://codingbat.com/doc/java-functional-filtering.html