Top "Hashmap" questions

Why Hashtable does not allow null keys or values?

As specified in JDK documentation, Hashtable does not allow null keys or values. HashMap allows one null key and any …

java hashmap hashtable

How to send hashmap value to another activity using an intent

How to send HashMap value from one Intent to second Intent? Also, how to retrieve that HashMap value in the …

android hashmap

Ruby - mapping an array to hashmap

I have an array, and a function that returns a value given a value. Ultimately I want to create a …

ruby hashmap

What is the time complexity of HashMap.containsKey() in java?

I need to know: What is the time complexity of HashMap.containsKey() in java?

java performance hashmap time-complexity

Thread safe Hash Map?

I am writing an application which will return a HashMap to user. User will get reference to this MAP. On …

java multithreading hashmap java.util.concurrent

How to swap keys and values in a hash

How do I swap keys and values in a Hash? I have the following Hash: {:a=>:one, :b=>:…

ruby hashmap

Is a HashMap thread-safe for different keys?

If I have two multiple threads accessing a HashMap, but guarantee that they'll never be accessing the same key at …

java multithreading thread-safety hashmap

Changing value after it's placed in HashMap changes what's inside HashMap?

If I create a new HashMap and a new List, and then place the List inside the Hashmap with some …

java hashmap pass-by-reference

How Can I create a generic HashMap to insert collections and objects?

How Can I instantiate a HashMap to put collections and objects?. //it's wrong Map<String,?>params=new HashMap&…

java generics hashmap java-6 java-5

Performance ConcurrentHashmap vs HashMap

How is the performance of ConcurrentHashMap compared to HashMap, especially .get() operation (I'm especially interested for the case of only …

java collections hashmap