How to convert List to Map ?

Collections conversion in Groovy can be achieved with some of collect* features. One of them, collectEntries(), iterates through given collection and returns a key-value pair. This pair is after stored in associated Map.

@Test
void "should convert List to Map"() {
  List<String> clubs = ["Arsenal", "Bastia", "Wolfsburg"]

  Map<String, String> clubsMap = clubs.collectEntries { entry ->
    return [entry.charAt(0).toString(), entry]
  }


  assertThat(clubsMap['A']).isEqualTo('Arsenal')
  assertThat(clubsMap['B']).isEqualTo('Bastia')
  assertThat(clubsMap['W']).isEqualTo('Wolfsburg')
}