### Question:
IntegerWrapper extends AbstractWrapper<Integer> implements NumberWrapper<Integer> { @Override public void increment() { Integer value = doGet(); if (value != null) { doSet(value + 1); } } IntegerWrapper();  IntegerWrapper(Integer value); @Override void set(Number v); @Override void increment(); @Override void decrement(); @Override R accept(WrapperVisitor<R, P, Q, TH> visitor, P p, Q q);  }### Answer:
@Test public void testIncrement() { IntegerWrapper wrapper = new IntegerWrapper(10); wrapper.increment(); assertEquals(new Integer(11), wrapper.get()); }