Java Equivalent for where in C#

Question

What is Java 8 equivalent method for where extension method in C#?

How can I filter element of a Hashtable in Java 8 using lambda expression

Yet another tutorial: http://docs.oracle.com/javase/tutorial/collections/streams/reduction.html — kajacx, Jun 02 '14 at 14:08

score 11 · Answer 1 · edited May 23 '17 at 11:58

You need to use the stream filter() function, which takes a Predicate object defining your filtering criteria.

Here's a useful tutorial. Note the usage:

List<User> olderUsers = users. 
                        stream().
                        filter(u -> u.age > 30).
                        collect(Collectors.toList());

and the subsequent collection into a collection type of your choice.

Note that I'd likely avoid Hashtable in preference to HashMap. See this useful SO entry.

score 3 · Accepted Answer · answered Jun 02 '14 at 14:08

3

Actually he's asking about hashtable, but there is not much a difference there.

        Hashtable<String, Integer> someHashTable;
        someHashTable.entrySet().stream().filter((entry)-> entry.getValue()>3).forEach(System.out::println);

Here's the tutorial I've used to understand java8 new features including streams http://winterbe.com/posts/2014/03/16/java-8-tutorial/ best one I've found so far. Enjoy :)

answered Jun 02 '14 at 14:08

vach

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also as Brian said below, Hashtable is a history use HashMap instead :) – vach Jun 03 '14 at 07:10

Java Equivalent for where in C#

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