code: public void ensureCapacity(int minCapacity) {
          modCount++;
          int oldCapacity = elementData.length;
          if (minCapacity > oldCapacity) {
              Object oldData[] = elementData;
              int newCapacity = (oldCapacity * 3) / 2 + 1;
              if (newCapacity < minCapacity)
                  newCapacity = minCapacity;
              // minCapacity is usually close to size, so this is a win:
              elementData = Arrays.copyOf(elementData, newCapacity);
          }
      }
docs: Increases the capacity of this <tt>IdentityArrayList</tt> instance, if
  necessary, to ensure that it can hold at least the number of elements
  specified by the minimum capacity argument.
  
  @param minCapacity the desired minimum capacity