Iterator - 单向仅可删除
hasNext()
next()
remove()
ListIterator - 双向可增改删
hasPrevious()
hasNext()
previous()
next()
add(Object)
set(Object)
remove()
Iterator - 单向仅可删除
hasNext()
next()
remove()
ListIterator - 双向可增改删
hasPrevious()
hasNext()
previous()
next()
add(Object)
set(Object)
remove()