### Question:
HMapID implements MapID, Cloneable, Serializable { @Override public void increment(int key) { if (this.containsKey(key)) { this.put(key, this.get(key) + 1.0); } else { this.put(key, 1.0); } } HMapID(int initialCapacity, float loadFactor);  HMapID(int initialCapacity);  HMapID();  HMapID(MapID m); int size(); boolean isEmpty(); double get(int key); boolean containsKey(int key); double put(int key, double value); void putAll(MapID m); double remove(int key); void clear(); boolean containsValue(double value); Object clone(); Set<Integer> keySet(); Collection<Double> values(); Set<MapID.Entry> entrySet(); String toString(); @Override void plus(MapID m); @Override double dot(MapID m); @Override void increment(int key); @Override void increment(int key, double value); double length(); void normalize(); MapID.Entry[] getEntriesSortedByValue(); MapID.Entry[] getEntriesSortedByValue(int n);  }### Answer:
@Test public void testIncrement() { HMapID m = new HMapID(); assertEquals(0.0, m.get(1), 10E-6); m.increment(1, 0.5); assertEquals(0.5, m.get(1), 10E-6); m.increment(1); m.increment(2, 0.0); m.increment(3, -0.5); assertEquals(1.5, m.get(1), 10E-6); assertEquals(0.0, m.get(2), 10E-6); assertEquals(-0.5, m.get(3), 10E-6); }