Can hash table have multiple values?

Can hash table have multiple values?

As mentioned earlier in the post, it is not possible to use the same key for different values in Hashtable(key, value). Although, you may create a List or some object as a value in the key/value pair of HashTable.

Can we add duplicate values and keys in hash table?

6 Answers. it can have duplicate values but not keys. If you wanted to associate multiple values with a key, you could place a reference to an array (or hash) at that key, and add the value to that array (or hash).

Can we store duplicate keys in Hashtable C#?

In hashtable, you can store elements of the same type and of the different types. The elements of hashtable that is a key/value pair are stored in DictionaryEntry, so you can also cast the key/value pairs to a DictionaryEntry. In Hashtable, key must be unique. Duplicate keys are not allowed.

What is Hashtable in Java?

Hashtable was part of the original java. It is similar to HashMap, but is synchronized. Like HashMap, Hashtable stores key/value pairs in a hash table. When using a Hashtable, you specify an object that is used as a key, and the value that you want linked to that key.

Can a Key have two values?

HashMap can be used to store key-value pairs. But sometimes you may want to store multiple values for the same key. For example: For Key A, you want to store – Apple, Aeroplane.

How HashMap hold multiple values in one key?

21 Answers

1. Use a map that has a list as the value. Map> .
2. Create a new wrapper class and place instances of this wrapper in the map. Map .
3. Use a tuple like class (saves creating lots of wrappers). Map> .
4. Use mulitple maps side-by-side.

What if we add duplicate keys in hash table?

As for values, multiple elements can have the same value in both hashes and arrays. Then: Duplicate keys not allowed.

Can we add duplicate keys in Dictionary C#?

In Dictionary, key must be unique. Duplicate keys are not allowed if you try to use duplicate key then compiler will throw an exception. In Dictionary, you can only store same types of elements.

Can we add duplicate values in Dictionary C#?

The Key value of a Dictionary is unique and doesn’t let you add a duplicate key entry. To accomplish the need of duplicates keys, i used a List of type KeyValuePair<> .

Is HashMap thread safe?

HashMap is non-synchronized. It is not thread-safe and can’t be shared between many threads without proper synchronization code whereas Hashtable is synchronized.

What if we add duplicate keys in Hashtable?

How do I put multiple values in a HashMap?

How to add multiple values per key to a Java HashMap

1. Stick with the standard APIs and add a collection class like a ‘Vector’ or ‘ArrayList’ to your map or set.
2. Use the MultiMap and MultiValueMap classes from the Apache Commons library.