May 5, 2012 · java,util.HashMap is a class, not a package, and there is nothing here that wasn't here five years ago.

Jan 30, 2013 · I need to create a hashmap with key as integer and it should hold multiple values of different data types. For example if the key is msg id and the values are message of type …

Jul 6, 2016 · I am using a Collection (a HashMap used indirectly by the JPA, it so happens), but apparently randomly the code throws a ConcurrentModificationException. What is causing it …

300 Lambda Expression Java 8 In Java 1.8 (Java 8) this has become lot easier by using forEach method from Aggregate operations (Stream operations) that looks similar to iterators from …

Apr 23, 2009 · How are we able to sort a HashMap<key, ArrayList>? I want to sort on the basis of a value in the ArrayList.

Sep 5, 2009 · 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 …

Is checking for key existence in HashMap always necessary? I have a HashMap with say a 1000 entries and I am looking at improving the efficiency. If the HashMap is being accessed very …

The above still results in Type safety: The expression of type HashMap needs unchecked conversion to conform to Map<String,String>. While this can be suppressed with …

Nov 4, 2009 · If I pass the same key multiple times to HashMap’s put method, what happens to the original value? And what if even the value repeats? I didn’t find any documentation on this. …

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