Last active
August 29, 2015 13:58
-
-
Save eyalgo/10110666 to your computer and use it in GitHub Desktop.
Safe get from map that holds Collection as value
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// The code | |
public static <T, V> Collection<V> safeGetCollectionFromMap(Map<T, ? extends Collection<V>> map, T key) { | |
if (map.get(key) != null) { | |
return map.get(key); | |
} else { | |
return Lists.newLinkedList(); | |
} | |
} | |
// The tests | |
//import static <package>.CollectionUtils.safeGetCollectionFromMap; | |
@Test | |
public void mapContainsKey_thenShouldReturnTheValue() { | |
Collection<String> values = Sets.newHashSet("v1", "v2"); | |
Map<String, Set<String>> map = ImmutableMap.<String, Set<String>>builder().put("the-key", Sets.newHashSet("v1", "v2")).build(); | |
assertThat(safeGetCollectionFromMap(map, "the-key"), equalTo(values)); | |
} | |
@Test | |
public void mapDoesNotContainsKey_thenShouldReturnEmpty() { | |
Map<String, Set<String>> map = ImmutableMap.<String, Set<String>>builder().put("the-key", Sets.newHashSet("v1", "v2")).build(); | |
assertThat(safeGetCollectionFromMap(map, "the-OTHER-key"), is(emptyCollectionOf(String.class))); | |
} | |
@Test | |
public void mapContainsKeyWithNullValue_thenShouldReturnEmpty() { | |
Map<String, Set<String>> map = new HashMap<String, Set<String>>(); | |
map.put("the-key", null); | |
assertThat(safeGetCollectionFromMap(map, "the-key"), is(emptyCollectionOf(String.class))); | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment