java - 将多个集合合并为一个集合并删除重复的集合

Question

我有 m 个集合，可以使用数组或数组列表存储。这些集合之间存在重叠。我想将这 m 个集合合并为一个集合，那些重复的元素只会在合并后的集合中占据一个位置。我应该使用什么样的数据结构和操作来构建组合集合。

Answer 1

参见:java.util.Set.addAll(集合)的 javadoc:

/**
 * Adds all of the elements in the specified collection to this set if
 * they're not already present (optional operation).  If the specified
 * collection is also a set, the <tt>addAll</tt> operation effectively
 * modifies this set so that its value is the <i>union</i> of the two
 * sets.  The behavior of this operation is undefined if the specified
 * collection is modified while the operation is in progress.