### Question:
DefaultKeyedValues implements KeyedValues, Cloneable,
        PublicCloneable, Serializable { public void clear() { this.keys.clear(); this.values.clear(); this.indexMap.clear(); } DefaultKeyedValues(); @Override int getItemCount(); @Override Number getValue(int item); @Override Comparable getKey(int index); @Override int getIndex(Comparable key); @Override List<Comparable> getKeys(); @Override Number getValue(Comparable key); void addValue(Comparable key, double value); void addValue(Comparable key, Number value); void setValue(Comparable key, double value); void setValue(Comparable key, Number value); void insertValue(int position, Comparable key, double value); void insertValue(int position, Comparable key, Number value); void removeValue(int index); void removeValue(Comparable key); void clear(); void sortByKeys(SortOrder order); void sortByValues(SortOrder order); @Override boolean equals(Object obj); @Override int hashCode(); @Override Object clone();  }### Answer:
@Test public void testClear() { DefaultKeyedValues v1 = new DefaultKeyedValues(); v1.addValue("A", 1.0); v1.addValue("B", 2.0); assertEquals(2, v1.getItemCount()); v1.clear(); assertEquals(0, v1.getItemCount()); }