Functional Programming in Java

Transforming a List

Manipulating a collection to produce another result is as easy as iterating through the elements of a collection. Suppose we’re asked to convert a list of names to all capital letters. Let’s explore some options to achieve this.

Java’s String is immutable, so instances can’t be changed. We could create new strings in all caps and replace the appropriate elements in the collection. However, the original collection would be lost; also, if the original list is immutable, like it is when created with Arrays.asList(), then the list can’t change. Another downside is it would be hard to parallelize the computations.

Creating a new list that has the elements in all caps is a better option.

That suggestion may seem quite naive at ...