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Oct 16, 2011 · 1. It's just an abstract example, it could be Map<Integer, String> to be casted to Map<Long, String>. – Mark. Oct 16, 2011 at 23:56. 2. If the latter is your concrete requirement, then you really have to loop over it. But if it was actually a Map<String, String> which is incorrectly been declared as Map<Object, Object>, then you could just ...
Map.of. Java 9 added a series of Map.of static methods to do just what you want: Instantiate an immutable Map using literal syntax. The map (a collection of entries) is immutable, so you cannot add or remove entries after instantiating. Also, the key and the value of each entry is immutable, cannot be changed.
Oct 8, 2009 · I'm searching a lightweight API (preferable single class) to convert a Map<String,String> map = new HashMap<String,String(); to XML and, vice versa, convert the XML back to a Map<String,
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 Interface. Just copy paste below statement to your code and rename the HashMap variable from hm to your HashMap variable to print out key-value pair. HashMap<Integer,Integer> hm ...
and the javadoc of Map.merge says: @throws NullPointerException if the specified key is null and this map does not support null keys or the value or remappingFunction is null. You can avoid the for loop by using the forEach method of your list. Map<Integer, Boolean> answerMap = new HashMap<>();
The official way to do this is to call map.entrySet(), which returns a set of Map.Entry, each of which contains a key and a value (entry.getKey() and entry.getValue()). In an idiosyncratic implementation, it might make some difference whether you use map.keySet(), map.entrySet() or something else.
Feb 3, 2009 · First tip. The 1st tip is that you can make a local reference to the map and you give it a SHORT name: private static final Map<Integer, String> myMap = new HashMap<>(); static {. final Map<Integer, String> m = myMap; // Use short name! m.put(1, "one"); // Here referencing the local variable which is also faster!
Jun 4, 2013 · The original answer with JavaConversions: You can use scala.collection.JavaConversions to implicitly convert between Java and Scala: import scala.collection.JavaConversions._. val myScalaMap = myJavaMap.mapValues(_.toSet) Calling mapValues will trigger an implicit conversion from the java Map to a scala Map, and then calling toSet on the java ...
Map<String,String> someMap = (Map<String,String>)getApplicationContext().getBean("someMap"); You use a legacy method that we generally don't want to use since that returns Object : Object getBean(String name) throws BeansException;
Jul 6, 2016 · In Java 8, you can use lambda expression: map.keySet().removeIf(key -> key condition); removeIf is a convenient default method in Collection which uses Iterator internally to iterate over the elements of the calling collection.
