In this example we will show how remove empty ArrayList from a list. In the first snippet of java code, we create a list with mock data then use an Iterator to loop over the list and remove empty instances. In the second snippet using java 8, the removeIf is used passing in a predicate that checks if the list is empty. Another way to perform the same operation is to convert the collection to a stream and filter empty elements.
Straight up Java
@Test
public void remove_empty_lists_java() {
List<List<String>> removeAllEmpty = Lists.newArrayList();
removeAllEmpty.add(Arrays.asList("abc", "def"));
removeAllEmpty.add(Arrays.asList("ghi"));
removeAllEmpty.add(Arrays.asList());
for (Iterator<List<String>> it = removeAllEmpty.iterator(); it
.hasNext();) {
List<String> elem = it.next();
if (elem.isEmpty()) {
it.remove();
}
}
assertEquals(2, removeAllEmpty.size());
}Java 8
@Test
public void remove_empty_lists_java8() {
List<List<String>> removeEmpty = Lists.newArrayList();
removeEmpty.add(Arrays.asList("abc", "def"));
removeEmpty.add(Arrays.asList("ghi"));
removeEmpty.add(Arrays.asList());
removeEmpty.removeIf(e -> e.isEmpty());
assertEquals(2, removeEmpty.size());
}