Java Coding Problems

24. Transforming strings

Let's assume that we have a string and we want to transform it into another string (for example, transform it into upper case). We can do this by applying a function such as Function<? super String,​ ? extends R>.

In JDK 8, we can accomplish this via map(), as shown in the following two simple examples:

// hello worldString resultMap = Stream.of("hello")  .map(s -> s + " world")  .findFirst()  .get();// GOOOOOOOOOOOOOOOOL! GOOOOOOOOOOOOOOOOL!String resultMap = Stream.of("gooool! ")  .map(String::toUpperCase)  .map(s -> s.repeat(2))  .map(s -> s.replaceAll("O", "OOOO"))  .findFirst()  .get();

Starting with JDK 12, we can rely on a new method named transform​(Function<? super String, ​? extends R> f). Let's rewrite the preceding ...