vaskoz’s gists

vaskoz / IsReflectionSlow.java

Created July 15, 2013 05:57

Is reflection in Java a performance killer? Run these tests to check for yourself. After compilation, just run with the command line below passing a list of any strings as command line input to args[].

	import java.lang.reflect.*;

	public class IsReflectionSlow {
	public static double rand() {
	return Math.random();
	}

	public static String constant() {
	return "constant";
	}

vaskoz / Deps.java

Created July 17, 2013 07:40

An example of "jdeps" command line tool in Java 8 with JDeps usage help and 3 different outputs of -v (verbose) -P (profile) and -R (recursive)

	import java.util.Set;
	import java.util.HashSet;

	public class Deps {
	public static void main(String[] args) {
	System.out.println(Math.random());
	Set<String> set = new HashSet<>();
	}
	}

vaskoz / Annotation.java

Last active December 19, 2015 23:49

	@interface Foo {}
	interface Bar {}
	public class Annotation {
	public static void main(String[] args) {
	System.out.println("Foo annotation super interfaces");
	for (Class<?> klazz : Foo.class.getInterfaces())
	System.out.println(klazz);
	System.out.println("Bar interface super interfaces");
	for (Class<?> klazz : Bar.class.getInterfaces())
	System.out.println(klazz);

vaskoz / PSort.java

Created July 22, 2013 03:50

	import java.util.Arrays;
	import java.time.*;

	public class PSort {
	public static void main(String[] args) {
	if (args.length != 2) {
	System.err.println("Usage: PSort [seq\|par] [data size int]");
	System.exit(1);
	}
	boolean parallel = "par".equals(args[0]);

vaskoz / FunctionDescriptorExamples.java

Last active December 20, 2015 22:58

Function Interface & Descriptor Examples from JLS 8 - JSR 335

	// Function descriptor examples:
	interface X { void m() throws IOException; }
	interface Y { void m() throws EOFException; }
	interface Z { void m() throws ClassNotFoundException; }
	interface XY extends X, Y {}
	interface XYZ extends X, Y, Z {}

	// XY has descriptor ()->void throws EOFException
	// XYZ has descriptor ()->void (throws nothing)

vaskoz / Null.groovy

Created August 13, 2013 03:29

Examples of how 'null' is less than everything in Groovy.

	println "null < ${Long.MIN_VALUE}: ${null < Long.MIN_VALUE}"
	println "null < ${Boolean.FALSE}: ${null < Boolean.FALSE}"
	println "false < true: ${false < true}"
	println "null < new Object(): ${null < new Object()}"
	println "null < null: ${null < null}"
	def data = ["1", 2, 3L, null, "foo"]
	println data.sort()

vaskoz / EffectivelyFinal.java

Created August 14, 2013 01:30

Examples of Lambda Expressions,

	void m1(int x) {
	int y = 1;
	foo(() -> x+y);
	// Legal: x and y are both effectively final.
	}

	void m2(int x) {
	int y;
	y = 1;
	foo(() -> x+y);

vaskoz / MethodReferences.java

Created August 14, 2013 04:14

Java 8 Method Reference examples from JLS 8

	System::getProperty
	String::length
	List<String>::size // explicit class type args
	List::size // inferred class type args, or generic
	int[]::clone
	T::tvarMember

	"abc"::length
	foo[x]::bar
	(test ? list.map(String::length) : Collections.emptyList())::iterator

vaskoz / MethodReferences.java

Created August 14, 2013 06:00

An example of method references using Java 8 Comparator static methods

	import java.util.Comparator;
	import java.util.List;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collections;
	import java.util.stream.Collectors;

	public class MethodReferences {
	public static void main(String[] args) {
	List<String> list = new ArrayList<String>(Arrays.asList("cat", null, "foo", "aces", "bar", null, "az", null, "bc"));

vaskoz / Jvm8Changes.java

Last active December 21, 2015 12:08

JSR-335 4 bytecode updates: invokeinterface, invokespecial, invokestatic, and invokevirtual

	interface I {
	default String hi() { return "hello"; }
	static String here() { return "i'm static"; }
	// NEXT LINE WILL NOT COMPILE. But JLS8 says private default methods are allowed.
	default private String you() { return "yoho"; } // Not implemented as of jdk8b103.
	}
	class C implements I {
	}
	public class Jvm8Changes {
	public static void main(String[] args) {

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