May 5, 2012 · 1 To get keys in HashMap, We have keySet () method which is present in java.util.Hashmap package. ex :

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 frequently, ...

805 Suppose we have a HashMap<String, Integer> in Java. How do I update (increment) the integer-value of the string-key for each existence of the string I find? One could remove and reenter the pair, …

Sep 6, 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 through the hashmap? What is …

Map<String, String> myMap = new HashMap<String, String>() {{ put("a", "b"); put("c", "d"); }}; However, the anonymous subclass might introduce unwanted behavior in some cases. This includes for …

Jun 15, 2012 · Java HashMap key value storage and retrieval Asked 13 years, 6 months ago Modified 4 years, 1 month ago Viewed 105k times

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 Iterable …

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 insertion order. H...

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. Case 1: …

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.) Method #1: …