Functional Programming in Java, 2nd Edition

Refactoring for-each

As Java programmers, we’ve come to like and extensively use the so-called for-each syntax, which is of the form for(Type variable: iterable). It’s a lot simpler than the traditional for loop when we don’t need the index and care only about the elements in a collection. But it’s not uncommon to use break and continue with both versions of for. The result is verbose code that takes effort to maintain in the long run. Let’s take a stab at refactoring code that uses for-each to functional style.

Keeping up with our tradition, let’s start with the tests:

refactoring/fpij/AgencyTest.java

public class AgencyTest {
  Agency agency;

  @BeforeEach
  public void init() {
    agency = new Agency();
  }

  @Test
  public ...