9.Nio三个重要变量

A container for data of a specific primitive type.A buffer is a linear, finite sequence of elements of a specific primitive type. Aside from its content, the essential properties of a buffer are its capacity, limit, and position:

• A buffer's capacity is the number of elements it contains. The capacity of a buffer is never negative and never changes.
• A buffer's limit is the index of the first element that should not be read or written. A buffer's limit is never * negative and is never greater than its capacity.

• A buffer's position is the index of the next element to be read or written. A buffer's position is never negative and is never greater than its limit.

  
  image.png