Groovy Gradle

So, what is Groovy?

Groovy vs Java

Default imports

import java.io.*;
import java.lang.*;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.net.*;
import java.util.*;
import groovy.lang.*;
import groovy.util.*;

Multi-methods

int method(String arg) { return 1; }
int method(Object arg) { return 2; }
Object o = "Object";
int result = method(o);

assertEquals(2, result);

assertEquals(1, result);

Array initializers

int[] array = { 1, 2, 3 };

int[] array = [ 1, 2, 3 ];

Package scope visibility

class Person {
    String name
}

class Person {
    @PackageScope String name
}

ARM blocks

Path file = Paths.get("/path/to/file");
Charset charset = Charset.forName("UTF-8");
try (BufferedReader reader = Files.newBufferedReader(file, charset)) {
    String line;
    while ((line = reader.readLine()) != null) {
        System.out.println(line);
    }
} catch (IOException e) {
    e.printStackTrace();
}

new File('/path/to/file').eachLine('UTF-8') {
   println it
}

Inner classes

Lambdas

Runnable run = () -> System.out.println("Run");
list.forEach(System.out::println);

Runnable run = { println 'run' }
list.each(this.&println)
list.each { println it }           // preferred, for simple cases
list.each { item -> println item } // preferred

GStrings

int val = 2;
assert "c".getClass() == String.class;
assert false == "c${val}".equals("c2");
assert true == ("c" + val).equals("c2");

def val = 2
assert 'c'.class == String
assert "c".class == String
assert "c${val}".class in GString

String and Character literals

// for single char strings, both are the same
assert ((char) "c").class == Character
assert ("c" as char).class == Character

// for multi char strings they are not
try {
    ((char) 'cx') == 'c'
    assert false: 'will fail - not castable'
} catch (GroovyCastException e) {
}
assert ('cx' as char) == 'c'
assert 'cx'.asType(char) == 'c'

Behaviour of ==

String a = new String("a");
String b = new String("a");
assert a != b;
assert true == a.equals(b);

String a = new String("a")
String b = new String("a")
assert a == b
assert true == a.equals(b)
assert false == a.is(b)

Additional keywords

Lets do this together

Features

Lessons learned

Integration

Expressive build language

High performance builds

org.gradle.daemon=true
org.gradle.configureondemand=true
org.gradle.parallel=true

Evolving

Use cases