TrieSet extends AbstractSet<String> { @Override public boolean remove(Object object) { return trie.remove(object, PRESENT); } TrieSet(); Set<String> startsWith(String prefix); @Override boolean add(String string); @Override boolean contains(Object object); @Override boolean remove(Object object); @Override Iterator<String> iterator(); @Override int size();  }
@Test void remove() { assertTrue(set.remove("app")); assertEquals(2, set.size()); assertFalse(set.remove("app")); }