问题描述
|
我有m套，可以使用数组或arraylist进行存储。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，而那些重复的元素将仅在合并的集合中占据一个位置。我应该使用哪种数据结构和操作来构造组合集。
解决方法
此代码将为您完成：
Set set = new HashSet();
ArrayList list = new ArrayList();
ArrayList list2 = new ArrayList(); //etc
Object[] array = new Object[]{};
Object[] array2 = new Object[]{}; // etc
set.addAll(list);
set.addAll(list2);
set.addAll(Arrays.asList(array));
set.addAll(Arrays.asList(array2));
// Call addAll as many times as you like
/**
* 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.
/**
* Join multiple sets into one.
*/
@SafeVarargs
private final <T> Set<T> join(Set<T>... sets)
{
Set<T> result = new HashSet<>();
if (sets == null)
return result;
for (Set<T> set : sets)
{
if (set != null)
result.addAll(set);
}
return result;
}