Click here to watch in Youtube :
https://www.youtube.com/watch?v=5e2pLtMO8HI&list=UUhwKlOVR041tngjerWxVccw
CollectionsExample.java
Output
https://www.youtube.com/watch?v=5e2pLtMO8HI&list=UUhwKlOVR041tngjerWxVccw
CollectionsExample.java
import java.util.Collections; import java.util.Map; import java.util.Set; import java.util.WeakHashMap; /* Method public static <E> Set<E> newSetFromMap(Map<E,Boolean> map) Parameters: map - the backing map Returns: the set backed by the map */ public class CollectionsExample { public static void main(String[] args) { Map<String, Boolean> map = new WeakHashMap<String, Boolean>(); System.out.println("Map is: " + map); /* * Returns a set backed by the specified map. The resulting set displays * the same ordering, concurrency, and performance characteristics as * the backing map. In essence, this factory method provides a Set * implementation corresponding to any Map implementation. There is no * need to use this method on a Map implementation that already has a * corresponding Set implementation (such as HashMap or TreeMap). */ Set<String> set = Collections.newSetFromMap(map); System.out.println("set is: " + set); set.add("Java"); set.add("C"); set.add(".Net"); System.out.println("Set is: " + set); System.out.println("Map is: " + map); } }
Map is: {} set is: [] Set is: [Java, C, .Net] Map is: {Java=true, C=true, .Net=true}
https://sites.google.com/site/javaee4321/java-collections/CollectionsDemo-newSetFromMap.zip?attredirects=0&d=1
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