Java 8 – This ain’t your grandpa’s Java

2012-10-08T22:11:52-05:00

Man, you shouldn’t public answers before deadline. I can’t see statement that your code comes from coursera.org . Your posts is linked from java.dzone.com and I’m almost sure your code has too many hints (so someone could lost fun from implementing own solution). Edit it pls.

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2012-10-08T23:34:48-05:00

I did mention that examples were inspired from progfun course. I was careful in not being a spoiler. I updated the post to be more generic. Hope this helps!

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	public class TweetUtil {

	public static void main(String[] args) {
	final List<String> keywords = Arrays.asList("brown", "fox", "dog", "pangram");
	final String tweet = "The quick brown fox jumps over a lazy dog. #pangram http://www.rinkworks.com/words/pangrams.shtml";

	exists(keywords, tweet);
	}

	public static boolean exists(List<String> keywords, String tweet) {
	for (String keyword : keywords) {
	if (tweet.contains(keyword)) return true;
	}
	return false;
	}
	}

	object TweetUtil {

	def main(args: Array[String]) {
	val keywords = List("brown", "fox", "dog", "pangram")
	val tweet = "The quick brown fox jumps over a lazy dog. #pangram http://www.rinkworks.com/words/pangrams.shtml"

	keywords.exists(tweet.contains)
	(keywords.foldLeft(false)( _ \|\| tweet.contains(_) ))
	}
	}

	List<String> google = Arrays.asList("android", "Android", "galaxy", "Galaxy", "nexus", "Nexus");

	List<String> apple = Arrays.asList("ios", "iOS", "iphone", "iPhone", "ipad", "iPad");

	List<Tweet> tweets = TweetReader.fromTweetSet(TweetReader.allTweets);

	// Using anyMatch and method reference
	List<Tweet> googleTweets = tweets.stream().filter(t -> (google.stream().anyMatch(t.text::contains))).collect(toList());

	List<Tweet> appleTweets = tweets.stream().filter(t -> (apple.stream().anyMatch(t.text::contains))).collect(toList());

	// Using reduce
	List<Tweet> googleTweets2 = tweets.stream().filter(t -> google.stream().reduce(false, (Boolean b, String keyword) -> b \|\| t.text.contains(keyword), (l, r) -> l \| r)).collect(toList());

	List<Tweet> appleTweets2 = tweets.stream().filter(t -> apple.stream().reduce(false, (Boolean b, String keyword) -> b \|\| t.text.contains(keyword), (l, r) -> l \| r)).collect(toList());

	package java.util.stream;

	import java.util.function.Predicate;

	public interface MyStream<T> extends Stream<T> {

	default boolean exists(Predicate<? super T> predicate) {
	return anyMatch(predicate);
	}
	}

	package java.util.stream;

	import java.util.Spliterator;
	import java.util.function.Predicate;
	import java.util.function.Supplier;

	public class MyReferencePipeline<T, U> extends ReferencePipeline<T, U> implements MyStream<U> {

	public MyReferencePipeline(Supplier<? extends Spliterator<?>> source, int sourceFlags, boolean parallel) {
	super(source, sourceFlags, parallel);
	}

	public MyReferencePipeline(Spliterator<?> source, int sourceFlags, boolean parallel) {
	super(source, sourceFlags, parallel);
	}

	@Override
	public boolean exists(Predicate<? super U> predicate) {
	return evaluate(MatchOps.makeRef(predicate, MatchOps.MatchKind.ANY));
	}
	}

Java 8 – This ain’t your grandpa’s Java

Published by Arul Dhesiaseelan

2 thoughts on “Java 8 – This ain’t your grandpa’s Java”

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	package java.util.stream;

	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collection;

	public class MyList<E> extends ArrayList<E> {

	public MyList(int initialCapacity) {
	super(initialCapacity);
	}

	public MyList() {
	super();
	}

	public MyList(Collection<? extends E> c) {
	super(c);
	}

	@Override
	public MyStream<E> stream() {
	return new MyReferencePipeline<>(Arrays.spliterator((E[]) this.toArray(), 0, this.size()), StreamOpFlag.IS_SIZED \| StreamOpFlag.IS_ORDERED, false);
	}

	@Override
	public Stream<E> parallelStream() {
	return new MyReferencePipeline<>(Arrays.spliterator((E[]) this.toArray(), 0, this.size()), StreamOpFlag.IS_SIZED \| StreamOpFlag.IS_ORDERED, true);
	}

	}

	// Run with -Xbootclasspath/p:target/classes as ReferencePipeline access is now package local, so use this trick
	List<Tweet> googleTweets3 = tweets.stream().filter(tweet -> (new MyList<>(google).stream().exists(tweet.text::contains))).collect(toList());

	List<Tweet> appleTweets3 = tweets.stream().filter(tweet -> (new MyList<>(apple).stream().exists(tweet.text::contains))).collect(toList());

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Published by Arul Dhesiaseelan

2 thoughts on “Java 8 – This ain’t your grandpa’s Java”

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