any direction would be gr8

[Dlangdaman]

I need to write a program that launches 1000 threads. Each thread adds 1 to a variable sum that is initially 0. I need to pass sum by reference to each thread. In order to pass by reference, define an Integer wrapper object to hold the sum. Run the program with and without synchronization to see the effects.

Ex output:

At thread 1 sum = 0;
At thread 2 sum = 1,
Etc…

im lost on how to start..I have some code Ill try to post later

[r035198x]

I need to write a program that launches 1000 threads. Each thread adds 1 to a variable sum that is initially 0. I need to pass sum by reference to each thread. In order to pass by reference, define an Integer wrapper object to hold the sum. Run the program with and without synchronization to see the effects.

Ex output:

At thread 1 sum = 0;
At thread 2 sum = 1,
Etc…

im lost on how to start..I have some code Ill try to post later

Till you post the code then we'll all keep our fingers crossed.

[JosAH]

I need to write a program that launches 1000 threads. Each thread adds 1 to a variable sum that is initially 0. I need to pass sum by reference to each thread. In order to pass by reference, define an Integer wrapper object to hold the sum. Run the program with and without synchronization to see the effects.

Ex output:

At thread 1 sum = 0;
At thread 2 sum = 1,
Etc…

im lost on how to start..I have some code Ill try to post later

Two remarks:

1) You can't pass anything by reference in Java; never; really.
2) Integers are immutable; you can't use them for your purposes.

No reason to panic though, you can write your own little class:

public class MutableInteger {
   private int i;
   public MutableInteger() { this(0); }
   public MutableInteger(int i) { this.i= i; }
 
   // increment i, (un) synced:
   public int inc() { return ++i; }
   public synchronized syncInc() { return ++i; }
}
 

simply pass one of those MutableInteger objects to your threads and increment away.

kind regards,

Jos

[Dlangdaman]

interesting how that was part of the requirments...? I am currently at work. I will post code later in the day, probably after 3:30...Thanks

[r035198x]

Two remarks:

1) You can't pass anything by reference in Java; never; really.
2) Integers are immutable; you can't use them for your purposes.

No reason to panic though, you can write your own little class:

public class MutableInteger {
   private int i;
   public MutableInteger() { this(0); }
   public MutableInteger(int i) { this.i= i; }
 
   // increment i, (un) synced:
   public int inc() { return ++i; }
   public synchronized syncInc() { return ++i; }
}
 

simply pass one of those MutableInteger objects to your threads and increment away.

kind regards,

Jos

It could have been ... enterprising to see is code first.

[Dlangdaman]

without synchronization?

import java.util.concurrent.*;
 
public class Threads {
    private Integer sum = new Integer(0);
 
    public static void main(String[]args) {
        Threads test = new Threads();
        System.out.println("What is Sum ? " + test.sum);
    }
    public Threads() {
        ExecutorService executor = Executors.newFixedThreadPool(1000);
        //Not sure right here?
          executor.shutdown();
 
          while(!executor.isTerminated()){
 
          }
    }
    //without synchronization
    class SumTask implements Runnable {
        public void run(){
            //not sure here?
        }
    }
}

no idea where to go from there

with syncronization

import java.util.Concurrent.*;
 
public class Threads2 {
    private Integer sum = new Integer(0);
 
    public synchronized static void main(String[]args) {
        Threads2 test = new Threads2();
    }
 
    public Threads2(){
        ExecutorService executor = Executors.newFixedThreadPool(1000);
        // dont know
    }
 
    executor.shutdown();
 
    while(!executor.isTerminated()){
    }
    // with sync
    class SumTask2 implements Runnable {
        public synchronized void run(){
            // dont know
        }
    }
}

Please help!

[JosAH]

without synchronization?

    private Integer sum = new Integer(0);
 

Please help!

You simply ignored my remark?

kind regards,

Jos

[Dlangdaman]

Im sorry, i dont follow..what did I do? i was doing this the way our instructor wants...i just need help to make it work....no disrespect meant...purely an accident

[Dlangdaman]

My most recent working code

how would I implement sychronization and without

import java.util.concurrent.*;
 
public class Thread {
  private Integer sum = new Integer(0);
 
  public static void main(String[] args) {
    Thread test = new Thread();
    System.out.println("What is sum ? " + test.sum);
  }
 
  public Thread() {
    ExecutorService executor = Executors.newFixedThreadPool(1000);
 
    for (int i = 0; i < 1000; i++) {
      executor.execute(new SumTask());
    }
 
    executor.shutdown();
 
    while(!executor.isTerminated()) {
    }
  }
 
  class SumTask implements Runnable {
    public void run() {
      int value = sum.intValue() + 1;
      sum = new Integer(value);
    }
  }
}

[Dlangdaman]

I just wanted to check and see if anyone is out there today

[JosAH]

I just wanted to check and see if anyone is out there today

I don't see why you're using an Integer instead of a simple int. But maybe that
is a (superfluous) requirement.

So what happens when you let all your threads increment that 'shared resource'
in an (un)synchronized way?

kind regards,

Jos