Method count

onjava/TypeCounter.java:16–23

(Object obj)

    this.baseType = baseType;
  }
  public void count(Object obj) {
    Class<?> type = obj.getClass();
    if(!baseType.isAssignableFrom(type))
      throw new RuntimeException(
        obj + " incorrect type: " + type +
        ", should be type or subtype of " + baseType);
    countClass(type);
  }
  private void countClass(Class<?> type) {
    Integer quantity = get(type);
    put(type, quantity == null ? 1 : quantity + 1);