2010年4月7日 · Hashmap is used for storing data in key value pairs. We can use a hashmap for storing objects in a application and use it further in the same application for storing, updating, …

What are the differences between a HashMap and a Hashtable in Java? Which is more efficient for non-threaded applications?

64 Map is an interface that HashMap implements. The difference is that in the second implementation your reference to the HashMap will only allow the use of functions defined in …

I'm using a HashMap. When I iterate over the map, the data is returned in (often the same) random order. But the data was inserted in a specific order, and I need to preserve the …

2009年7月1日 · Since all maps in Java implement the Map interface, the following techniques will work for any map implementation (HashMap, TreeMap, LinkedHashMap, Hashtable, etc.) …

As you have HashMap<String, HashMap>, you would need two loops - one for the outer and one for the inner HashMap. Btw - you should definitively type the second HashMap - don't know …

2013年3月26日 · I am still new to object instantiation, and wonder what to do to initialize a HashMap of HashMaps. When inserting new observations into the classifier, I can create a …

Apart from the fact that HashSet does not allow duplicate values, what is the difference between HashMap and HashSet in their implementation? It's a little bit vague because both use hash …

For a hash table resolving collisions with chaining (like Java's hashmap) this is technically O (1+α) with a good hash function, where α is the table's load factor. Still constant as long as the …

2009年9月6日 · If I have the value "foo", and a HashMap<String> ftw for which ftw.containsValue("foo") returns true, how can I get the corresponding key? Do I have to loop …