Questions on HW8-Fall07

Questions on HW8-Fall07

Ask questions on homework 8 here.

Question: What is the difference between escaping and not getting harmed?? aren't they the same??

Not being harmed is more like the zombie missed trying to hit you, but it's still trying to attack you. Escaping means that zombie is no longer after you trying to attack you at all. Dawn Finney.

Question: When a person kills a zombie, will he rise again??

I like to think of killing a zombie as like decapitation or something similar to where the zombie won't rise again. I think otherwise the humans would just have a terrible survival rate. Dawn Finney.

Question: Can you put up the criteria for this homework please?

Continue to work on functionality. It will be posted shortly. Joel Uthe

Question: What happens if two or more zombies are within 20 steps of a person, but coming at him from different directions? Which direction should he turn to?

The person should run away from the closest one. If they are the same distance then you can just choose the first one he finds. This is mainly up to you, but be sure to document what you do. Joel Uthe

Question: How do we get our methods to recognize the timesteps?

If you look in the Agent class then there are 2 .act methods. One takes in a timestep (something that you may want to consider doing), but then doesn't handle it. Go ahead and attempt to overwrite the method that takes the parameter instead of the other one. If you look at the .run(..) method in Simulation.java then this is the actual driver of the simulation. It calls .act() with the parameter with each Agent so you know it is getting passed, but just not acted upon. Joel Uthe

Question: Do we have to submit a Word document, or can we submit one from Excel?

You should submit a Word document, because you not only need include graphs but also explanations for your results. Dawn Finney.

Question: What is the speed supposed to be?

15 Joel Uthe

Question: what speed is this?

This is the max movement (speed) for each time step. It is actually just a suggestion because you should find a speed (and size of World) that allows an environment that will give you good results. If there aren't any Zombies left before you ever institute a Special Tactical Maneuver then it wouldn't be a very good test on what works and what doesn't. In this case consider upping the speed for the zombies so it is easier for them to eat. Joel Uthe

Question: Are we suppose to create a main method? Or do we call the simulation from the command line???

The better idea is to write a main method. You will be running your simulation several times and it will be easier for you in the long run. Dawn Finney.

Question: How long is the default time step?

However long it takes to run through all the agents and have them act once. Dawn Finney.

How does the act(t) method work? I don't understand if it acts for a period (t) or waits (t) before acting? Thanks

The .act(int t) method has no different functionality then the .act() method. All it does it extra is pass the current time step as a parameter. Right now in the Agent class, this just gets ignored and it calls the other .act() because the timestep is not usually needed. But depending on how students have written their simulation it may be useful to use the .act(int t) method so they have access to the timestep. It doesn't wait, or only act for that time, it just gives them access to what time it is. For example if I was an actor on an assembly line then I do the same thing everyday. I don't need to know what day it is to complete my task, but if It wouldn't hurt me if I was told what day it is. That is what .act(int t) does. Joel Uthe

How do I write to a file?

The file writing is already built into Simulation.java. After each timestep the simulation class the .endStep(int timestep) method. If the simulation has a file to write to then it does. So how do you give it a file to write to? Before calling .run(), call openFile(FileChooser.getMediaPath("myResults.txt")) and it will now have a file to write to. And then what does it write? It writes whatever is returned from your .lineForFile(). You'll need to modify your simulation to correctly return the number of persons, zombies, and dead. Joel Uthe

How do I count the number of Zombies and number of Persons?

Create a new method to run through your agents REMOVEDkedList that is in Simulation.java. Keep a counter for each person and zombie that you find (be sure to cast since agents is full of Agent class items). Joel Uthe

I am using two classes PersonAgent and ZombieAgent, how do I tell if the agent that is returned is a zombie or a person?

In your if statement you can use the 'instanceof' comparison. if(current instanceof ZombieAgent) will return true if it is a Zombie. Joel Uthe

What graphs should I turn in?

Turn in 9 graphs (three trails for each run) and then average your final results for each run. So you will be turning in 9 graphs and 3 averages. Joel Uthe

What is the Attack range?

If it a zombie's turn to move and he is within the distance of a person then he should move right on top of it and execute the percentages that is in bullet 3 of the description. Joel Uthe

What is chase mode?

Chase mode means that for this step and subsequent steps the zombie will continue to chase the person. You will need to put the zombie in chaseMode (maybe a boolean) and keep track of his target for future .act() calls when it will continue to chase that person. Joel Uthe

We have two classes, HumanAgent and ZombieAgent. When a person dies, how do we add it to the zombie linked list?

After changing the person's color to green, we have:
ZombieAgent.allZombies.add(this); // adds this element to the allZombies linked list
allHumans.remove(this); // removes this element from the allHumans linked list

This compiles, but at runtime, we are getting a ClassCastException due to the first line.

This is because you are trying to add this (a HumanAgent) to the zombie list (required to be a ZombieAgent). Instead of adding this. Try making a new ZombieAgent using the values in your current human and then adding that to your list. Joel Uthe

Question: How do you guys want us to turn in the files? in other words, should we turn in our zombiesimulation so that when the TA's run it, it will do all three methods, or did you want each scenario (no tactics, and the two tactics) to have their own zombiesimulation.java file?

Usually we just want the last version with two tactical maneuvers. Dawn Finney.

When we try to run(#) our ZombieAttackSimulation we get an "OutOfMemoryError: Java heap space" after 50 Timesteps. We tried running on different computers but we're still getting the same thing. How do we resolve this?

Question: On the question about the Drjava heap space... do you know where in the book it explains how to do add more? I know I have read it somewhere, but now I can't find it.

Taken from Spring '07. The book has changed, but it is in the book on how to change the heapspace.
No clue, but your program really shouldn't be using all of Java's heap space anyway. Dawn Finney.
I don't know what page it is on, but there is a way to do it. Put the arguments -Xmx32m in JVM Arguments for Interactions JVM in Edit>Preferences>Miscellaneous where 32m stands for 32 megabytes. it must be a power of 2 and either m(mega) or k(kilo) bytes. Dawn is correct though, your program shouldn't be using all of Java's default heap space, and your TA's WILL NOT GRADE WITH AN INCREASED HEAP SPACE even if you ask them to. It is another error that is causing the problem, not just your computer. Joel Uthe

If we created a human and zombie agent from agent how can we remove dead humans from the list of humans contained in the simulation?

allHumans.remove(this) is a guess. It really depends on how your lists are implemented, but there is probably a built-in remove method. Joel Uthe
Just do it! Dawn Finney.

Do dead humans and zombies count as humans and zombies or not at all?

Dead humans are not humans, and dead zombies are not zombies. You may still want to keep track of the results (it is pretty easy...initial count-still living humans-still living zombies) so you can graph the casualties of your tactics. Joel Uthe

What happens if the zombie dies on the first timestep?

It is rare, but it happens. I wouldn't use it as one of your graphs, but it is up to you. Joel Uthe
I'd say definitely don't use this graph. TAs are less likely to award full points to a flat graph with an explanation of "oh our zombie died on the first timestep." Dawn Finney.

Question: How do we make the timesteps step? Our simulation initializes, but it doesn't progress.

Call run(). Dawn Finney.

Question: We did call run() and it doesnt progress

Did you overwrite the .run() that is included in Simulation.java? Look there to see how a simulation truly runs. If you didn't overwrite any of it, can you get your other simulations to run? Joel Uthe
Your screen isn't refreshing. Try calling repaint(). Dawn Finney
So we didnt overwrite run, and other simulations worked. we had already written in a repaint. We are just going to go to Ricardo's office hours and hope that he has some insight to our code. -Rachel

Question: Our human and zombie classes are both extended from agent, not agentnode. How can get a zombie to be removed or added from the simulations master list of zombies/humans? Would the same work for a human's death? .

Just remove it. You're just removing an item from a linkedlist. Yeah the same would go for a human. I usually discourage removing anything from a list while you are still iterating through it (You'll probably get CurrentModificationExceptions). I usually just have a boolean marking the human or zombie as dead and therefore will do nothing in the act method. Dawn Finney.

Question: Will the grading criteria be up soon?

Ask Joel. Dawn Finney.

Question: Joel,Will the grading criteria be up soon?

The grading criteria will not be released until after the assignment. Each step of the assignment will be equally important, so continue to step through each piece of functionality. Joel Uthe

QuestionIf a human dies, but has not come back and it hits time step 99, do we count them among the dead, since they are about to come back, but haven't yet?

It's still a dead human so neither an alive human nor a zombie. Honestly how many times is this case going to happen? Dawn Finney.

I just had 3 dead humans at the end of a run.

Man your zombies are weak. Mine usually just take over the entire screen. Well graph them as you like then. Just note in your explanation which category you place the dead humans. Dawn Finney.

Can you post the criteria?

See above answer. Joel Uthe

When will submit all of our files do we still only submit it with just one person to TSquare and e-mail the TA as to which one it is?

See above answer. But turn in the file with both special tactics implemented, but make sure it is well commented so your grading TA can tell which code to comment out to test all simulations. Joel Uthe

For some reason my output writer is not working.... It creates the txt file but it doesn't write on it. I have tried everything
ideas pleaseee

You have to remember to close the file. Dawn Finney.

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Homeworks-Fall 2007 last edited on 23 December 2007 at 7:08 pm by adsl-152-173-97.asm.bellsouth.net