Given Groovy Who Needs Java

Given Groovy Who Needs Java?

Prof Russel Winder
http://www.russel.org.uk

email: russel@winder.org.uk
xmpp: russel@winder.org.uk
twitter: @russel_winder

Copyright © 2012 Russel Winder 1

Interstitial Advertisement


Introduction


Groovy was…
● …designed to be a dynamic symbiote to Java.

● Java is statically typed.
● Groovy is optionally typed.


Groovy was…
● …designed to have a very lightweight syntax.

● Literal syntax for lists and maps.
● As little punctuation as possible.


Groovy was…
● …designed to work with code as first class entity.

● Closures and functional approach from the outset.
● No waiting for Java 8.


Code


println 'Hello World.'


public class testAll_GroovyTestCase extends GroovyTestCase {
void test_helloWorld_trivial() {
assert 'helloWorld_trivial.groovy'.execute().text == 'Hello World.n'
}
}

Power asserts

JUnit3 behind the scenes


@Grab('org.spockframework:spock:0.7-groovy2.0')
import spock.lang.Specification

class TestAll_Spock extends Specification {
def "ensure the hello world program prints hello world"() {
expect:
'helloWorld_trivial.groovy'.execute().text == 'Hello World.n'
}
}


def datum = ['Hello', ' ', 'World', '.'].join('')

println datum


String datum = ['Hello', ' ', 'World', '.'].join('')

println datum


datum = ['Hello', ' ', 'World', '.'].join('')

println datum


words = [:]

words.third = 'World'
words << [first: 'Hello', fourth: '.']
words['second'] = ' '

sequence = ['first', 'second', 'third', 'fourth']

println(sequence.collect{words[it]}.join(''))

@GrabResolver(name='atlassian',
root='https://maven.atlassian.com/content/groups/public/')
@Grab('org.swift.tools:gint:1.5.0')
import org.swift.tools.Gint

includeTool << Gint

gint.initialize(this)

new File('.').eachFileMatch(~/helloWorld_.*.groovy/) {
gint.add(name: it.name, inline: { it.name.execute().text == 'Hello World.n' })
}

gint.finalizeTest()

import groovy.xml.MarkupBuilder

new MarkupBuilder().html{
head{
title 'Hello World.'
}
body{
(0 ..< 3).each {
em('Hello')
}
}
}

<html>
 <head>
 <title>Hello World.</title>
 </head>
 <body>
 Hello
 Hello
 Hello
 </body>
</html>

html = new XmlParser().parse(System.in)
assert html.head.title.text() == 'Hello World.'
assert html.body.em.text() == 'HelloHelloHello'


import javax.swing.WindowConstants

import groovy.swing.SwingBuilder

def widget = new SwingBuilder().frame(
title: 'Hello World Window',
size: [200, 100],
defaultCloseOperation: WindowConstants.EXIT_ON_CLOSE
){
panel {
button(text:'Say Hello', actionPerformed: { println 'Hello.' })
}
}
widget.show()


final n = 100000
final delta = 1.0 / n
final startTime = System.nanoTime()
def sum = 0.0
for (i in 1 .. n) { sum += 1 / (1 + ((i - 0.5) * delta) ** 2) }
final pi = 4 * delta * sum
final elapseTime = (System.nanoTime() - startTime) / 1e9
Output.out(getClass().name, pi, n, elapseTime)


final int n = 1000000000
final double delta = 1.0 / n
final startTimeNanos = System.nanoTime()
double sum = 0.0
for (int i = 1; i <= n; ++i) {
final double x = (i - 0.5d) * delta
sum += 1.0d / (1.0d + x * x)
}
final double pi = 4.0 * delta * sum
final elapseTime = (System.nanoTime() - startTimeNanos) / 1e9

import groovy.transform.CompileStatic

@CompileStatic execute() {
final int n = 1000000000
final startTimeNanos = System.nanoTime ()
double sum = 0.0
for (int i = 1; i <= n; ++i) {
sum += 1.0d / (1.0d + x * x)
}
final double pi = 4.0 * delta * sum
}

execute()

final int n = 10000000
final double pi = 4.0 * delta * (1i .. n).sum {int i ->
1.0d / (1.0d + x * x)
}


import groovy.transform.CompileStatic

@CompileStatic execute() {
final int n = 10000000
final double pi = 4.0 * delta * (double)((1i .. n).sum {int i ->
1.0d / (1.0d + x * x)
})
}

execute()


import groovyx.gpars.ParallelEnhancer

void execute(final numberOfTasks) {
final n = 1000000000
final delta = 1.0 / n
final startTimeNanos = System.nanoTime ()
final sliceSize = (int)(n / numberOfTasks)
final items = 0 ..< numberOfTasks
ParallelEnhancer.enhanceInstance(items)
final pi = 4.0 * delta * items.collectParallel {taskId ->
PartialSum.dynamicCompile(taskId, sliceSize, delta)
}.sumParallel()
Output.out(getClass().name, pi, n, elapseTime, numberOfTasks)
}

execute 1
execute 2
execute 8
execute 32

static double dynamicCompile(final int taskId, final int sliceSize, final double delta) {
final int start = 1i + taskId * sliceSize
final int end = (taskId + 1i) * sliceSize
double sum = 0.0d
for (int i = start; i <= end; ++i) {
sum += 1.0d / (1.0d + x * x)
}
sum
}

Conclusion


There is nothing that Java can do

that Groovy cannot do better.


Interstitial Advertisement



Prof Russel Winder



Challenge


Problem

Groovy
Java

Develop faster
Execute faster
Can be done at all



Prof Russel Winder



Given Groovy Who Needs Java

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Semelhante a Given Groovy Who Needs Java

Semelhante a Given Groovy Who Needs Java (20)

Mais de Russel Winder

Mais de Russel Winder (20)

Último

Último (20)

Given Groovy Who Needs Java