Re: are lambdas a way to bring functional programming to java?

On Fri, 27 Jun 2014 16:50:44 -0700 (PDT), gdotone@gmail.com wrote,
quoted or indirectly quoted someone who said :


        // create a new HashMap
        final Map<String, Integer> h = new HashMap<>( 149 /* capacity
*/, 0.75f /* loadfactor */ );
        {
        // add some key/value pairs about English measure to the
HashMap
        h.put( "inch", 1 );
        h.put( "foot", 12 );
        h.put( "yard", 36 );
        h.put( "mile", 3760 * 36 );
        }

Compare old style enumerating a HashMap

 out.println( "enumerate all the key/value Entries in the HashMap" );
        for ( Map.Entry<String, Integer> entry : h.entrySet() )
            {
            // prints lines of the form foot=12
            // in effectively random order.
            // this does not require an expensive get lookup to find
the value
            String key = entry.getKey();
            int value = entry.getValue();
            out.println( "separately: " + key + " " + value );
            }

Lambda style:

 out.println( "enumerate all the key/value Entries in the HashMap
using Java 1.8 lambda dual foreach" );
            h.forEach( ( unit, measure ) -> {
            out.println( unit + " -> " + measure );
            // this effectively creates an anonymous class with an
anonymous method that prints two values.
            // h.forEach traverses the hasMap and calls that method
for each key/value pair.
            // Javac automatically infers the types from the
declaration for h.
  
--
Roedy Green Canadian Mind Products http://mindprod.com
The art of strongly-typed language design is largely arranging
that errors are automatically detected as soon as possible
in the compose, compile, run cycle.