除了HashSet不允许重复值之外,HashMap和HashSet之间还有什么区别呢?
我是说执行方面?这有点模糊,因为两者都使用哈希表来存储值。
除了HashSet不允许重复值之外,HashMap和HashSet之间还有什么区别呢?
我是说执行方面?这有点模糊,因为两者都使用哈希表来存储值。
当前回答
HashSet是一个集合,例如{1,2,3,4,5}
HashMap是key ->值(键到值)映射,例如{a -> 1, b -> 2, c -> 2, d -> 1}
注意,在我上面的例子中,HashMap中不能有重复的键,但它可能有重复的值。
在HashSet中,必须没有重复的元素。
其他回答
HashSet是根据HashMap实现的。它是键和PRESENT对象之间的映射。
HashSet是一个集合,例如{1,2,3,4,5}
HashMap是key ->值(键到值)映射,例如{a -> 1, b -> 2, c -> 2, d -> 1}
注意,在我上面的例子中,HashMap中不能有重复的键,但它可能有重复的值。
在HashSet中,必须没有重复的元素。
HashSet和HashMap都是存储对,区别在于在HashMap中你可以指定一个键,而在HashSet中键来自对象的哈希代码
HashSet
HashSet class implements the Set interface In HashSet, we store objects(elements or values) e.g. If we have a HashSet of string elements then it could depict a set of HashSet elements: {“Hello”, “Hi”, “Bye”, “Run”} HashSet does not allow duplicate elements that mean you can not store duplicate values in HashSet. HashSet permits to have a single null value. HashSet is not synchronized which means they are not suitable for thread-safe operations until unless synchronized explicitly.[similarity] add contains next notes HashSet O(1) O(1) O(h/n) h is the table
HashMap
HashMap class implements the Map interface HashMap is used for storing key & value pairs. In short, it maintains the mapping of key & value (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls.) This is how you could represent HashMap elements if it has integer key and value of String type: e.g. {1->”Hello”, 2->”Hi”, 3->”Bye”, 4->”Run”} HashMap does not allow duplicate keys however it allows having duplicate values. HashMap permits single null key and any number of null values. HashMap is not synchronized which means they are not suitable for thread-safe operations until unless synchronized explicitly.[similarity] get containsKey next Notes HashMap O(1) O(1) O(h/n) h is the table
更多信息请参考这篇文章。
HashMap是用来添加、获取、删除…由任何类型的自定义键索引的对象。 HashSet用于添加元素,删除元素,并通过比较它们的哈希值来检查元素是否存在。
HashMap包含元素,HashSet记住它们的哈希值。