Lambdaj Closure in Java

Yesterday we played around with the Lambdaj project. The project provides a fancy way to simulate closure in Java. Here some simple examples based on the lambda4j documentation code.

	import static ch.lambdaj.Lambda.*;
	import static ch.lambdaj.collection.LambdaCollections.*;
	import static org.hamcrest.Matchers.*;
	import java.util.List;
	import javax.swing.JLabel;
	import ch.lambdaj.collection.*;
	import ch.lambdaj.function.closure.*;
	public class LambdaDemo {
	public static void main(String[] args) {
	// Simple lambda4j closure demo
	JLabel label = new JLabel("Test Label Name");
	Closure closure = closure(); {of(label).getText();}
	System.out.println(closure.apply());
	// Simple lambda4j collection demos
	LambdaList<Person> list = with(new Person("Michael Jackson"), new Person("Bob"));
	System.out.println(joinFrom(list).getName());
	// Select elements from a collection
	List<Person> select = select(list, having(on(Person.class).getName(), equalTo("Bob")));
	System.out.println(joinFrom(select).getName());
	// println each person to system.out
	Closure1<Person> personClosure = closure(Person.class); {of(System.out).println(var(Person.class));}
	personClosure.each(list);
	}
	static class Person
	{
	private String name;
	public Person(String name) {
	this.name = name;
	}
	public String getName() {
	return name;
	}
	public void setName(String name) {
	this.name = name;
	}
	@Override
	public String toString() {
	return name;
	}
	}
	}

view raw LambdaDemo.java hosted with ❤ by GitHub

And here a second example with "delayedClosure", which shows how to read a file line by line with lambda4j.

	import static ch.lambdaj.Lambda.*;
	import java.io.*;
	import ch.lambdaj.function.closure.*;
	public class FileReaderDemo {
	public static void main(String[] args) {
	File file = new File(FileReaderDemo.class.getResource("/demo.txt").getFile());
	FileReader reader = new FileReader(file);
	reader.eachLine(); {
	of(System.out).println(var(String.class));
	}
	}
	public static class FileReader {
	private final File file;
	public FileReader(File file) {
	this.file = file;
	}
	public void eachLine() {
	delayedClosure(new DelayedClosure<Void>() {
	@Override
	public Void doWithClosure(Closure lineReader) {
	BufferedReader reader = null;
	try {
	InputStream stream = new FileInputStream(file);
	reader = new BufferedReader(new InputStreamReader(stream));
	for (String line = reader.readLine(); line != null; line = reader.readLine()) {
	lineReader.apply(line);
	}
	} catch (IOException ioe) {
	throw new RuntimeException("Error while reading file " + file, ioe);
	} finally {
	try {
	if (reader != null) reader.close();
	} catch (IOException ioe) {
	throw new RuntimeException("Error while closing file reader", ioe);
	}
	}
	return null;
	}
	});
	}
	}
	}

view raw FileReaderDemo.java hosted with ❤ by GitHub

More details about lambda4j please have a look at the project website:
http://code.google.com/p/lambdaj/