### Question:
FilterList implements Filter<K, T> { public void addFilter(Filter<K, T> filter) { this.filters.add(filter); } FilterList();  FilterList(final List<Filter<K, T>> rowFilters);  FilterList(final Operator operator);  FilterList(final Operator operator, final List<Filter<K, T>> rowFilters); List<Filter<K, T>> getFilters(); Operator getOperator(); void addFilter(Filter<K, T> filter); @Override void readFields(DataInput in); @Override void write(DataOutput out); @Override boolean filter(K key, T persistent);  }### Answer:
@Test public void testAddFilter() { filterList = new FilterList<>(Operator.MUST_PASS_ALL, fList); int a = 3; for (int i = 0; i < 10; i++) { filterList.addFilter(new SingleFieldValueFilter<String, WebPage>()); assertEquals(a++, filterList.getFilters().size()); } }