import java.util.concurrent.CopyOnWriteArrayList;
public class CopyOnWriteArrayTest {
CopyOnWriteArrayList<String> basket = new CopyOnWriteArrayList<String>();
Thread fruit;
Thread vegatable;
Thread bean;
Thread keepSize;
Thread takeFromBasket;
public CopyOnWriteArrayTest() {
fruit = new Thread(new Runnable() {
String [] fruit = {
"Apple",
"Apricot",
"Avocado",
"Banana",
"Blackberry",
"Orange"
};
@Override
public void run() {
while(true)
{
try {
for(int i = 0; i < fruit.length; i++)
basket.add(fruit[i]);
Thread.sleep(1);
} catch (InterruptedException e) {
return;
}
}
}
});
fruit.start();
vegatable = new Thread(new Runnable() {
String [] vegatable = {
"Bok choy",
"Cabbage",
"Catsear",
"Celery",
"Spinach"
};
@Override
public void run() {
while(true)
{
try {
for(int i = 0; i < vegatable.length; i++)
basket.add(vegatable[i]);
Thread.sleep(1);
} catch (InterruptedException e) {
return;
}
}
}
});
vegatable.start();
bean = new Thread(new Runnable() {
String [] bean = {
"pea",
"ricebean",
"black-eyed pea",
"soybean",
"peanuts"
};
@Override
public void run() {
while(true)
{
try {
for(int i = 0; i < bean.length; i++)
{
if(bean[i] == "peanuts")
System.out.println("Peanuts has been added.");
basket.add(bean[i]);
}
Thread.sleep(5000);
} catch (InterruptedException e) {
return;
}
}
}
});
bean.start();
keepSize = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
if(basket.size() > 20)
basket.remove(0);
if(Thread.interrupted())
return;
}
}
});
keepSize.start();
takeFromBasket = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
try {
int i = basket.indexOf("peanuts");
if(i != -1)
{
basket.remove("peanuts");
System.out.println("Peanut is found. Size: " + basket.size());
}
Thread.sleep(1);
} catch (InterruptedException e) {
return;
}
}
}
});
takeFromBasket.start();
}
void Stop()
{
fruit.interrupt();
vegatable.interrupt();
bean.interrupt();
keepSize.interrupt();
takeFromBasket.interrupt();
}
public static void main(String[] args) throws InterruptedException {
CopyOnWriteArrayTest c = new CopyOnWriteArrayTest();
Thread.sleep(120000);
c.Stop();
}
}
ArrayBlockingQueue in Java
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;
public class ArrayBlockingQueueTest {
ArrayBlockingQueue<String> b = new ArrayBlockingQueue<String>(10, true);
Thread t1;
Thread t2;
String text = "India’s recent series of power blackouts, "
+ "in which 600 million people lost electricity for "
+ "several days, reminds us of the torrid pace at which "
+ "populations in the developing world have moved onto "
+ "the powergrid. Unfortunately, this great transition "
+ "has been so rapid that infrastructure has mostly been "
+ "unable to meet demand. India itself has failed to meets "
+ "its own power capacity addition targets every year since "
+ "1951. This has left roughly one quarter of the country’s "
+ "population without any (legal) access to electricity. "
+ "That’s 300 million people out of a population of 1.2 "
+ "billion. Indeed, it is the daily attempt of the underserved "
+ "to access power that may have led to India’s recent grid crash.";
class Writing implements Runnable
{
@Override
public void run() {
int i = 0;
String [] p = text.split(" ");
while(true)
{
try {
b.put(p[i]);
} catch (InterruptedException e) {
break;
}
i++;
if(i == p.length)
i = 0;
}
}
}
class Reading implements Runnable
{
@Override
public void run() {
while(true)
{
try {
for(int i = 0; i < 5; i++)
{
String t = b.poll(500, TimeUnit.MILLISECONDS);
System.out.print(t + " ");
}
Thread.sleep(500);
} catch (InterruptedException e) {
break;
}
}
}
}
public void Stop()
{
t1.interrupt();
t2.interrupt();
}
public ArrayBlockingQueueTest() {
t1 = new Thread(new Writing());
t1.start();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
t2 = new Thread(new Reading());
t2.start();
}
public static void main(String[] args) throws InterruptedException {
ArrayBlockingQueueTest a = new ArrayBlockingQueueTest();
Thread.sleep(6000);
a.Stop();
}
}
Semaphore in Java
import java.util.concurrent.*;
public class SemaphoreThread {
static public class runThreadClass implements Runnable
{
Semaphore s;
int i, count;
public runThreadClass(int i, Semaphore s) {
this.i = i;
count = i + 2;
this.s = s;
}
public void run() {
try {
s.acquire();
System.out.println("Thread " + i + ". Work for " + count + " seconds.");
Thread.sleep(count * 1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
s.release();
}
}
public static void main(String[] args) {
final Semaphore s = new Semaphore(4);
for(int i = 0; i < 10; i++)
new Thread(new runThreadClass(i + 1, s)).start();
}
}
CountDownLatch in Java
import java.util.concurrent.*;
public class CountdownThread {
public static void main(String[] args) {
final CountDownLatch signal = new CountDownLatch(4);
class runnable implements Runnable
{
int id;
int length;
public runnable(int id, int length) {
this.id = id;
this.length = length;
}
@Override
public void run() {
try {
System.out.println("Thread " + id + ". Doing something for " + length + " seconds.");
Thread.sleep(length * 1000);
signal.countDown();
System.out.println("Thread " + id + ". Done. Waiting now.");
signal.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Thread " + id + " done.");
}
}
new Thread(new runnable(1, 4)).start();
new Thread(new runnable(2, 3)).start();
new Thread(new runnable(3, 2)).start();
new Thread(new runnable(4, 1)).start();
}
}
Threads using Executors in Java
import java.util.concurrent.*;
public class ThreadsWithExecutor {
public static void main(String[] args) {
ExecutorService service = Executors.newCachedThreadPool();
service.execute(new Runnable() {
@Override
public void run() {
System.out.println("thread1");
}
});
service.execute(new Runnable() {
@Override
public void run() {
System.out.println("thread2");
}
});
service.execute(new Runnable() {
@Override
public void run() {
System.out.println("thread3");
}
});
Future<Integer> f = service.submit(new Callable<Integer>() {
@Override
public Integer call() throws Exception {
return 100;
}
});
try {
System.out.println(f.get());
} catch (Exception e) {
e.printStackTrace();
}
service.shutdown();
try {
service.awaitTermination(100, TimeUnit.SECONDS);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("\nScheduling Thread");
ScheduledExecutorService scheduledExecutor = Executors.newScheduledThreadPool(10);
scheduledExecutor.schedule(new Runnable() {
@Override
public void run() {
System.out.println("This thread runs after 5 seconds wait");
}
}, 5, TimeUnit.SECONDS);
scheduledExecutor.schedule(new Runnable() {
@Override
public void run() {
System.out.println("This thread runs after 7 seconds wait");
}
}, 7, TimeUnit.SECONDS);
scheduledExecutor.shutdown();
}
}
Threading in Java
import java.util.Random;
public class ThreadTutorial {
static class ThreadClass1
{
boolean stop = false;
void DoSomething()
{
Random r = new Random();
r.nextInt();
}
public synchronized void thinking()
{
DoSomething();
System.out.println("thinking for 2 seconds");
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized void reading()
{
DoSomething();
System.out.println("reading for 1 seconds");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public ThreadClass1()
{
Thread t1 = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
thinking();
if(stop != false)
break;
}
}
});
t1.start();
Thread t2 = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
reading();
if(stop != false)
break;
}
}
});
t2.start();
try {
Thread.sleep(60000);
} catch (InterruptedException e) {
e.printStackTrace();
}
stop = true;
try {
t1.join();
t2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
static class ThreadClass2
{
boolean stop = false;
Object o1 = new Object();
Object o2 = new Object();
void DoSomething()
{
Random r = new Random();
r.nextInt();
}
public void readingHarddrive()
{
DoSomething();
synchronized (o1) {
System.out.println("reading hard drive for 2 seconds");
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void writingHarddrive()
{
DoSomething();
synchronized (o1) {
System.out.println("writing hard drive for 1 seconds");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void readingDatabase()
{
DoSomething();
synchronized (o2) {
System.out.println("reading database for 5 seconds");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void writingDatabase()
{
DoSomething();
synchronized (o2) {
System.out.println("writing database for 4 seconds");
try {
Thread.sleep(4000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public ThreadClass2()
{
Thread t1 = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
readingDatabase();
if(stop != false)
break;
}
}
});
t1.start();
Thread t2 = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
writingDatabase();
if(stop != false)
break;
}
}
});
t2.start();
Thread t3 = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
readingHarddrive();
if(stop != false)
break;
}
}
});
t3.start();
Thread t4 = new Thread(new Runnable() {
@Override
public void run() {
while(true)
{
writingHarddrive();
if(stop != false)
break;
}
}
});
t4.start();
try {
Thread.sleep(60000);
} catch (InterruptedException e) {
e.printStackTrace();
}
stop = true;
try {
t1.join();
t2.join();
t3.join();
t4.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) throws InterruptedException {
new ThreadClass1();
System.out.println("------------------------------------------------------");
new ThreadClass2();
}
}
ToString in C#
class Person
{
string fname;
string lname;
public Person(string fname, string lname)
{
this.fname = fname;
this.lname = lname;
}
public override string ToString()
{
return fname + " " + lname;
}
}
class Program
{
static void Main(string[] args)
{
Person p = new Person("John", "Smith");
Console.WriteLine(p);
}
}
toString in Java
public class ToStringTest {
static class Person
{
String fname;
String lname;
public Person(String fname, String lname) {
this.fname = fname;
this.lname = lname;
}
@Override
public String toString()
{
return fname + " " + lname;
}
}
public static void main(String[] args) {
Person p = new Person("John", "Smith");
System.out.println(p);
}
}
HashCode in C#
Another hashcode example
class Program
{
class Person
{
public Person(String fname, String lname)
{
this.fname = fname;
this.lname = lname;
}
String fname;
String lname;
public int hashCode()
{
return (fname.GetHashCode() * 1021) ^ lname.GetHashCode();
}
public bool equals(Object obj)
{
return this.fname.Equals(((Person)obj).fname) &&
this.lname.Equals(((Person)obj).lname);
}
}
class Point
{
public Point(int x, int y)
{
this.x = x;
this.y = y;
}
int x;
int y;
public int hashCode()
{
return (x * 31) ^ y;
}
public bool equals(Object obj)
{
return x == ((Point)obj).x &&
y == ((Point)obj).y;
}
}
static char[] getLowerCase()
{
char[] temp = new char[26];
for (int i = 0; i < 26; i++)
temp[i] = (char)(i + 97);
return temp;
}
static char[] getUpperCase()
{
char[] temp = new char[26];
for (int i = 0; i < 26; i++)
temp[i] = (char)(i + 65);
return temp;
}
static String getName(char[] lower, char[] upper)
{
Random r = new Random();
StringBuilder sb = new StringBuilder();
int count = r.Next(10);
for (int j = 0; j < count; j++)
{
int index = r.Next(25);
if (j == 0)
sb.Append(upper[index]);
else
sb.Append(lower[index]);
}
return sb.ToString();
}
static void AnalyzePerson()
{
char [] lower = getLowerCase();
char [] upper = getUpperCase();
Hashtable table = new Hashtable();
Person []list = new Person[500000];
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
for(int i = 0; i < 500000; i++)
{
String fname = getName(lower, upper);
String lname = getName(lower, upper);
Person p = new Person(fname, lname);
table.Add(p, i);
list[i] = p;
}
stopwatch.Stop();
Console.WriteLine("putting: " + stopwatch.ElapsedMilliseconds + " ms");
stopwatch.Restart();
for(int i = 0; i < 500000; i++)
{
Person p = list[i];
object o = table[p];
}
stopwatch.Stop();
Console.WriteLine("getting: " + stopwatch.ElapsedMilliseconds + " ms");
}
static void AnalyzePoint()
{
Hashtable table = new Hashtable();
Point []list = new Point[500000];
Random r = new Random();
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
for(int i = 0; i < 500000; i++)
{
Point p = new Point(r.Next(50), r.Next(100));
table.Add(p, i);
list[i] = p;
}
stopwatch.Stop();
Console.WriteLine("putting: " + stopwatch.ElapsedMilliseconds + " ms");
stopwatch.Restart();
for(int i = 0; i < 500000; i++)
{
Point p = list[i];
object o = table[p];
}
stopwatch.Stop();
Console.WriteLine("getting: " + stopwatch.ElapsedMilliseconds + " ms");
}
static void Main(string[] args)
{
AnalyzePoint();
AnalyzePerson();
}
}
HashCode in Java
import java.util.Hashtable;
import java.util.Random;
public class HashCode {
static class Person
{
public Person(String fname, String lname) {
this.fname = fname;
this.lname = lname;
}
String fname;
String lname;
public int hashCode()
{
return (fname.hashCode() * 1021) ^ lname.hashCode();
}
public boolean equals(Object obj)
{
return this.fname.equals(((Person)obj).fname) &&
this.lname.equals(((Person)obj).lname);
}
}
static class Point
{
public Point(int x, int y) {
this.x = x;
this.y = y;
}
int x;
int y;
public int hashCode()
{
return (x * 31) ^ y;
}
public boolean equals(Object obj)
{
return x == ((Point)obj).x &&
y == ((Point)obj).y;
}
}
static Character [] getLowerCase()
{
Character []temp = new Character[26];
for(int i = 0; i < 26; i++)
temp[i] = (char)(i + 97);
return temp;
}
static Character [] getUpperCase()
{
Character []temp = new Character[26];
for(int i = 0; i < 26; i++)
temp[i] = (char)(i + 65);
return temp;
}
static String getName(Character[] lower, Character[] upper)
{
Random r = new Random();
StringBuilder sb = new StringBuilder();
int count = r.nextInt(10);
for(int j = 0; j < count; j++)
{
int index = r.nextInt(25);
if(j == 0)
sb.append(upper[index]);
else
sb.append(lower[index]);
}
return sb.toString();
}
static void AnalyzePerson()
{
Character [] lower = getLowerCase();
Character [] upper = getUpperCase();
Hashtable<Person, Integer> table = new Hashtable<Person, Integer>();
Person []list = new Person[500000];
long pastTime = System.currentTimeMillis();
for(int i = 0; i < 500000; i++)
{
String fname = getName(lower, upper);
String lname = getName(lower, upper);
Person p = new Person(fname, lname);
table.put(p, i);
list[i] = p;
}
long currentTime = System.currentTimeMillis();
System.out.println("putting: " + (currentTime - pastTime));
pastTime = System.currentTimeMillis();
for(int i = 0; i < 500000; i++)
{
Person p = list[i];
table.get(p);
}
currentTime = System.currentTimeMillis();
System.out.println("getting: " + (currentTime - pastTime));
}
static void AnalyzePoint()
{
Hashtable<Point, Integer> table = new Hashtable<Point, Integer>();
Point []list = new Point[500000];
Random r = new Random();
long pastTime = System.currentTimeMillis();
for(int i = 0; i < 500000; i++)
{
Point p = new Point(r.nextInt(50), r.nextInt(100));
table.put(p, i);
list[i] = p;
}
long currentTime = System.currentTimeMillis();
System.out.println("putting: " + (currentTime - pastTime));
pastTime = System.currentTimeMillis();
for(int i = 0; i < 500000; i++)
{
Point p = list[i];
table.get(p);
}
currentTime = System.currentTimeMillis();
System.out.println("getting: " + (currentTime - pastTime));
}
public static void main(String[] args) {
AnalyzePoint();
AnalyzePerson();
}
}
Random Code Generator 