Why java.util.Hashtable marked as 'obsolete collection' in Netbeans 8?

Question

When I import java.util.Hashtable in my code in Netbeans 8 the IDE suggest that it is obsolete collection. Why?

Answer 1

Read the documentation !

As of the Java 2 platform v1.2, this class was retrofitted to implement the Map interface, making it a member of the Java Collections Framework. Unlike the new collection implementations, Hashtable is synchronized. If a thread-safe implementation is not needed, it is recommended to use HashMap in place of Hashtable. If a thread-safe highly-concurrent implementation is desired, then it is recommended to use ConcurrentHashMap in place of Hashtable.