how to add or copy an arraylist to the inner class which is an arraylist of objects?

Programming Questions

chunkyork..

how to add or copy an arraylist to the inner class which is an arraylist of objects?

in Programming Questions • 3 years ago

decided to start a new post - further to recent discussion " ".

i still can't solve this.

I understand what PhiLho is suggesting in his last response but i don't understand how to do it.

I have tried to simplify my problem in the code below.

in this sketch there are three composite objects (families; each being a mother with 3 kids. one daughter and two sons.)

each family is a friend of the others - bar one child - who deletes one friend - only that one child should have a different friends list .

but this prints out:

1: girls friends[2, 3]
1: 0: boys friends[2, 3]
1: 1: boys friends[2, 3]
2: girls friends[1, 3]
2: 0: boys friends[1, 3]
2: 0: i've had a fight with friend 3!
2: 1: boys friends[1]
3: girls friends[1, 2]
3: 0: boys friends[1, 2]
3: 1: boys friends[1, 2]

the highlight shows that the brother (being an element of the same arrayList 'boys') has also had this friend removed.

I understand that i have setup the classes in a way that the list is referenced to the 'boys' rather than being copied. But i cannot figure out how to do this copy or how to add the values in way other than i have; so that "if you remove a reference from one, it will still be in the other"

can anyone explain how i can do this please. thanks!

ps: this runs with the xml file data added below at end

pss: i have looked at clone() but i don't understand how to implement it.

//sketch of family relations
//3 families: each family is a unit being
//a mother with 3 children: One daughter and Two sons.
//each family is friends with the others
//
//OOP properties:
//each family member is a class-object
//Mother class is composed of children -
//daughter and son classes are inner classes of mother class
//sons are in an arrayList
XMLElement xml;
int mums = 3;
Mother [] mum = new Mother [mums];
void setup() {
//load family relations from file
xml = new XMLElement(this, "relations.xml");
mums = xml.getChildCount();
XMLElement family;
XMLElement identity;
XMLElement friend1;
XMLElement friend2;
for (int i=0; i<mum.length; i++) {
family = xml.getChild(i);
//get family relations
friend1 = family.getChild(0);
int mate1 = friend1.getIntAttribute("mate1");
friend2 = family.getChild(1);
int mate2 = friend2.getIntAttribute("mate2");
mum[i] = new Mother(1+i);
//add friends
mum[i].friends.add(mate1);
mum[i].girl.friends.add(mate1);
mum[i].friends.add(mate2);
mum[i].girl.friends.add(mate2);
}
}
void draw() {
for (int i = 0; i < mum.length; i++) {
mum[i].transmit();
}
}
/*................................................*/
int kids = 2;
class Mother {
Daughter girl;
ArrayList boys;
ArrayList friends = new ArrayList();
int ref;
Mother(int id) {
girl = new Daughter(id);
ref = id;
boys = new ArrayList();
for (int i=0; i<kids; i++) {
boys.add(new Son(id, i, friends));
}
}
void transmit() {
girl.display();
for (int i=0; i<boys.size(); i++) {
Son maleChild = (Son) boys.get(i);
maleChild.display();
}
}
}
/*................................................*/
class Daughter {
int id;
ArrayList friends = new ArrayList();
Daughter(int identity) {
id = identity;
}
void display() {
println(id + ": " + "girls friends" + friends);
}
}
/*................................................*/
class Son {
int id;
int who;
ArrayList friends = new ArrayList();
Son(int identity, int whom, ArrayList buddies) {
id = identity;
who = whom;
friends = buddies;
}
void display() {
println(id + ": " + who + ": " + "boys friends" + friends);
//remove the friend of one son
if ((id == 2) && (who == 0)) {
println(id + ": " + who + ": i've had a fight with friend 3!");
for (int i=0; i<friends.size(); i++) {
int fallenOutWith = (Integer) friends.get(i);
if (fallenOutWith == 3) {
friends.remove(new Integer(fallenOutWith));
}
}
}
}
}

XML file data:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<families>
<family>
<friend mate1="2"/>
<friend mate2="3"/>
</family>
<family>
<friend mate1="1"/>
<friend mate2="3"/>
</family>
<family>
<friend mate1="1"/>
<friend mate2="2"/>
</family>
</families>

Replies(9)

PhiLho

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

Hello, just a quick answer to show I am on the topic.
Making a simpler sketch illustrating the issue is an excellent idea, as I can play with it and improve it, showing the right direction...
I first took your example sketch and slightly improved it to better illustrate the issue: the fight happens only on user click. And I display mum's friends.

XMLElement xml;
int mums = 3;
Mother[] mum = new Mother[mums];
void setup() {
//load family relations from file
xml = new XMLElement(this, "relations.xml");
mums = xml.getChildCount();
XMLElement family;
XMLElement identity;
XMLElement friend1;
XMLElement friend2;
for (int i=0; i<mum.length; i++) {
family = xml.getChild(i);
//get family relations
friend1 = family.getChild(0);
int mate1 = friend1.getIntAttribute("mate1");
friend2 = family.getChild(1);
int mate2 = friend2.getIntAttribute("mate2");
mum[i] = new Mother(1+i);
//add friends
mum[i].friends.add(mate1);
mum[i].girl.friends.add(mate1);
mum[i].friends.add(mate2);
mum[i].girl.friends.add(mate2);
}
noLoop();
}
void draw() {
for (int i = 0; i < mum.length; i++) {
mum[i].transmit();
}
}
void mousePressed()
{
//remove the friend of one son
Son son = (Son) mum[1].boys.get(0);
println(2 + ": " + 0 + ": i've had a fight with friend 3!");
for (int i = 0; i < son.friends.size(); i++) {
int fallenOutWith = (Integer) son.friends.get(i);
println(fallenOutWith);
if (fallenOutWith == 3) {
son.friends.remove(new Integer(fallenOutWith));
println("removed");
}
}
redraw();
}
/*................................................*/
int kids = 2;
class Mother {
Daughter girl;
ArrayList boys;
ArrayList friends = new ArrayList();
int ref;
Mother(int id) {
girl = new Daughter(id);
ref = id;
boys = new ArrayList();
for (int i=0; i<kids; i++) {
boys.add(new Son(id, i, friends));
}
}
void transmit() {
display();
girl.display();
for (int i=0; i<boys.size(); i++) {
Son maleChild = (Son) boys.get(i);
maleChild.display();
}
}
void display() {
println(ref + ": " + "mum's friends" + friends);
}
}
/*................................................*/
class Daughter {
int id;
ArrayList friends = new ArrayList();
Daughter(int identity) {
id = identity;
}
void display() {
println(id + ": " + "girl's friends" + friends);
}
}
/*................................................*/
class Son {
int id;
int who;
ArrayList friends = new ArrayList();
Son(int identity, int whom, ArrayList buddies) {
id = identity;
who = whom;
friends = buddies;
}
void display() {
println(id + ": " + who + ": " + "boy's friends" + friends);
}
}

Funnily, it shows that the way you manage girls makes their friend list independent of the others...
One issue is that you first share the array list, then populate them.
Another issue is your direct usage of class fields. It is a good illustration that using setters (and getter) in some cases can help. We often omit them in the simple code of most Processing sketches, but sometime (here!), they are helpful because prcisely they can do more than just storing / giving back the values.
I will come back with a better class structure.

chunkyork..

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

i've managed to do it with same class structure - my problem was that i could'nt work out the right syntax to access the 'boys' array to do the adding. Your code pointed me in the right direction...Thanks!

basically added at line 26 of yours above:

    for (int j=0; j<mum[i].boys.size(); j++) {
      Son son = (Son) mum[i].boys.get(j);
      son.freinds.add(mate1);
      son.freinds.add(mate2);
    }

and removed the referencing bit.

what do you mean by the use of "setters and getter"?

I'm very interested in your thoughts on an alternative/better class structure for this.

complete code

XMLElement xml;
int mums = 3;
Mother [] mum = new Mother [mums];

void setup() {
//load family relations from file
xml = new XMLElement(this, "relations.xml");
mums = xml.getChildCount();
XMLElement family;
XMLElement identity;
XMLElement freind1;
XMLElement freind2;

for (int i=0; i<mum.length; i++) {
    family = xml.getChild(i);
    //get family relations
    freind1 = family.getChild(0);
    int mate1 = freind1.getIntAttribute("mate1");
    freind2 = family.getChild(1);
    int mate2 = freind2.getIntAttribute("mate2");

    mum[i] = new Mother(1+i);
    //add freinds
    mum[i].freinds.add(mate1);
    mum[i].girl.freinds.add(mate1);
    mum[i].freinds.add(mate2);
    mum[i].girl.freinds.add(mate2);
    for (int j=0; j<mum[i].boys.size(); j++) {
      Son son = (Son) mum[i].boys.get(j);
      son.freinds.add(mate1);
      son.freinds.add(mate2);
    }
}
noLoop();
}

void draw() {
   for (int i = 0; i < mum.length; i++) {
    mum[i].transmit();
}
}

void mousePressed() {
    //remove the freind of one son
    for (int i=0; i<mum.length; i++) {
      for (int j=0; j<mum[i].boys.size(); j++) {
        Son son = (Son) mum[i].boys.get(j);
        if ((son.id == 2) && (son.who == 0)) {
          println(son.id + ": " + son.who + ": i've had a fight with freind 3!");
          for (int k=0; i<son.freinds.size(); k++) {
            int fallenOutWith = (Integer) son.freinds.get(k);
            if (fallenOutWith == 3) {
              son.freinds.remove(new Integer(fallenOutWith));
            }
          }
        }
      }
    }
    redraw();
}

/*.....................................................................*/

int kids = 2;

class Mother {
Daughter girl;
ArrayList boys;
ArrayList freinds = new ArrayList();
int ref;

Mother(int id) {
    girl = new Daughter(id);
    ref = id;
    boys = new ArrayList();
    for (int i=0; i<kids; i++) {
      boys.add(new Son(id, i));
    }
}

void transmit() {
   println(ref + ": " + "mums freinds" + freinds);
   girl.display();
   for (int i=0; i<boys.size(); i++) {
     Son maleChild = (Son) boys.get(i);
     maleChild.display();
    }
}

}

/*.....................................................................*/

class Daughter {
int id;
ArrayList freinds = new ArrayList();

Daughter(int identity) {
id = identity;
}

void display() {
println(id + ": " + "girls freinds" + freinds);
}

}

/*.....................................................................*/

class Son {
int id;
int who;
ArrayList freinds = new ArrayList();

Son(int identity, int whom) {
    id = identity;
    who = whom;
}

void display() {
    println(id + ": " + who + ": " + "boys freinds" + freinds);
}

}

blindfish

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

setters and getters are methods added to your class specifically to set and retrieve the values of class properties. So rather than directly referencing a property with dot notation (e.g. MyClass.classProperty) you'd have a method to set the property and another method to return it. This example might help explain why this approach can be better than a direct reference:

MyClass {
int age;
MyClass() {
// constructor
}
// setter method
void setAge(int age) {
If(age >=0) {
this.age = age;
}
else {
age = 0;
println("Age cannot be less than 0!");
}
}
// getter method
int getAge() {
return age;
}
}

The advantage is more obvious on the setter method: as you can see it's possible to add error checking to make sure the input values are within accepted bounds and in fact do all kinds of other processing e.g. converting from one number type to another. The advantage on the getter method is less obvious and I must admit I can't think of a good example right now; though perhaps when working with arrays you might want to return a copy of the array rather than a reference as this will avoid code outside of your class from making a change to it...

Actually thinking about it, in strict OOP you'd usually make a variable private to ensure it couldn't be changed by direct reference (note this isn't easily achieved in Processing) - so the setter method is the only way to change the variable from outside the class - but that also means you can't retrieve it, which is why you need the getter method, even if it does little more than return a value.

chunkyork..

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

Thanks blindfish, i think i understand - need to look into this a bit more yet.

Having managed to do it by accessing the class directly (e.g. MyClass.classProperty) so far i'd like to see if the next problem is still possible this way.....

i've extended the "family relations example" been using so that a new son is added to the arraylist (boys) of each mum object.

Adding another son is fine, but again the problem doing this is adding with a copy of the arraylist freinds.

i get the error "Cannot make a static reference to the non-static field Son.freinds" and the line of code highlighted

Son.freinds.add(buddy);

I know that the correct arraylist is being accessed (println(buddy)) but how to add this arraylist to the agent being constructed in void giveBirth(); is again the same problem - though its different as can't call the agent in a for statement here.

I want to add a copy of the arraylist here when the object is constructed, but can't access it directly cause its being constructed?!?!? Would you know how to refer to the object being created here please - or is it possible this way?

thanks.

XMLElement xml;
int mums = 3;
Mother [] mum = new Mother [mums];
public ArrayList familyFreinds;

for (int i=0; i<mum.length; i++) {
    family = xml.getChild(i);
    //get family relations
    freind1 = family.getChild(0);
    int mate1 = freind1.getIntAttribute("mate1");
    freind2 = family.getChild(1);
    int mate2 = freind2.getIntAttribute("mate2");

    mum[i] = new Mother(1+i);
    //add freinds
    mum[i].freinds.add(mate1);
    mum[i].girl.freinds.add(mate1);
    mum[i].freinds.add(mate2);
    mum[i].girl.freinds.add(mate2);
    familyFreinds = new ArrayList();
    familyFreinds.add(mate1);
    familyFreinds.add(mate2);
    for (int j=0; j<mum[i].boys.size(); j++) {
      Son son = (Son) mum[i].boys.get(j);
      son.freinds.add(mate1);
      son.freinds.add(mate2);
    }
}
noLoop();
}

void draw() {
   println("family relations");
   for (int i = 0; i < mum.length; i++) {
    mum[i].transmit();
    if (mousePressed && (mouseButton == RIGHT)) {
      mum[i].giveBirth();
    }
}
}

void mousePressed() {
if (mouseButton == LEFT) {
    //remove the freind of one son
    for (int i=0; i<mum.length; i++) {
      for (int j=0; j<mum[i].boys.size(); j++) {
        Son son = (Son) mum[i].boys.get(j);
        if ((son.id == 2) && (son.who == 0)) {
          println(son.id + ": " + son.who + ": i've had a fight with freind 3!");
          for (int k=0; i<son.freinds.size(); k++) {
            int fallenOutWith = (Integer) son.freinds.get(k);
            if (fallenOutWith == 3) {
              son.freinds.remove(new Integer(fallenOutWith));
            }
            }
          }
        }
      }
    }
    redraw();
}

/*.....................................................................*/

int kids = 2;

class Mother {
Daughter girl;
ArrayList boys;
ArrayList freinds = new ArrayList();
int ref;
int boyCount = kids;

Mother(int id) {
    girl = new Daughter(id);
    ref = id;
    boys = new ArrayList();
    for (int i=0; i<kids; i++) {
      boys.add(new Son(id, i));
    }
}

void transmit() {
   println(ref + ": " + "mums freinds" + freinds);
   girl.display();
   for (int i=0; i<boys.size(); i++) {
     Son maleChild = (Son) boys.get(i);
     maleChild.display();
    }
}

void giveBirth() {
    boys.add(new Son(ref, boyCount++)) ;

    for (int i=0; i<mum[ref-1].freinds.size(); i++) {
      int buddy = (Integer) mum[ref-1].freinds.get(i);

      //println(buddy);
      Son.freinds.add(buddy);
    }
}

}

/*.....................................................................*/

class Daughter {
int id;
ArrayList freinds = new ArrayList();

Daughter(int identity) {
id = identity;
}

void display() {
println(id + ": " + "girls freinds" + freinds);
}

}

/*.....................................................................*/

PhiLho

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

OK, I had some time to finish the code to illustrate my idea:

XMLElement xml;
int mums = 3;
Mother[] mum = new Mother[mums];
void setup() {
//load family relations from file
xml = new XMLElement(this, "relations.xml");
mums = xml.getChildCount();
XMLElement family;
XMLElement identity;
XMLElement friend1;
XMLElement friend2;
for (int i = 0; i < mum.length; i++) {
family = xml.getChild(i);
//get family relations
friend1 = family.getChild(0);
int mate1 = friend1.getIntAttribute("mate1");
friend2 = family.getChild(1);
int mate2 = friend2.getIntAttribute("mate2");
mum[i] = new Mother(1+i);
//add friends
mum[i].addFriend(mate1);
mum[i].addFriend(mate2);
}
noLoop();
}
void draw() {
for (int i = 0; i < mum.length; i++) {
mum[i].transmit();
}
}
void mousePressed()
{
//remove the friend of one son
Son son = mum[1].getBoy(1);
son.removeFriend(3);
redraw();
}
/*................................................*/
int kids = 2;
class Mother {
Daughter girl;
ArrayList boys;
ArrayList friends = new ArrayList();
int ref;
Mother(int id) {
girl = new Daughter(id);
ref = id;
boys = new ArrayList();
for (int i = 0; i < kids; i++) {
boys.add(new Son(id, i+1));
}
}
void transmit() {
girl.display();
for (int i = 0; i < boys.size(); i++) {
Son maleChild = getBoy(i+1);
maleChild.display();
}
}
Son getBoy(int id)
{
if (id < 1 || id > boys.size())
return null; // or throw exception or return "empty" boy
return (Son) boys.get(id-1);
}
void addFriend(int id)
{
friends.add(id);
girl.addFriend(id);
for (int i = 0; i < boys.size(); i++) {
Son maleChild = getBoy(i+1);
maleChild.addFriend(id);
}
}
void removeFriend(int fallenOutWith)
{
friends.remove(new Integer(fallenOutWith));
}
void display() {
println(ref + ": " + "mum's friends" + friends);
}
}
/*................................................*/
class Daughter {
int id;
ArrayList friends = new ArrayList();
Daughter(int identity) {
id = identity;
}
void addFriend(int id)
{
friends.add(id);
}
void removeFriend(int fallenOutWith)
{
println(id + ": girl: i've had a fight with friend " + fallenOutWith + "!");
friends.remove(new Integer(fallenOutWith));
}
void display() {
println(id + ": " + "girl's friends" + friends);
}
}
/*................................................*/
class Son {
int id;
int who;
ArrayList friends = new ArrayList();
Son(int identity, int whom) {
id = identity;
who = whom;
}
void addFriend(int id)
{
friends.add(id);
}
void removeFriend(int fallenOutWith)
{
println(id + ": " + who + ": i've had a fight with friend " + fallenOutWith + "!");
friends.remove(new Integer(fallenOutWith));
}
void display() {
println(id + ": " + who + ": " + "boy's friends" + friends);
}
}

This code also answers blindfish's question about getters: the getBoy method in the Mother class allows to check the input and react accordingly to indicate an error: can be an assert (only checked when coding/testing, not in production, eg. in a private method) or the test I show (always active, useful in a public API). We can take a default value (first son), return null (calling code must test that), return an empty Son (supposing it then does nothing), throw an exception (must be caught in calling code), etc. It also shifts the index to make it more natural ("son 1" instead of "son 0").
Getters also hide the implementation: if I want to change the ArrayList to an HashSet or some more complex structure, I am free to do it as the calling code doesn't see it. It just knows it can get a son, whatever the way they are stored.

The addFriend isn't a real setter but is similar: it simplifies code, hide implementation (external code doesn't access internal list) and enforces rules (initially friends of the mother are friends of the children).
And since there is no longer shared array list, a son can remove a friend and the latter is still friend with the siblings.

chunkyork..

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

Thanks PhilLho, i see the benefit of setters and getters now.

Further to my post above (28-Jun-2010 09:37 AM) i have tried to extend your new code so that when the right button of the mouse is pressed a new son is born. The problem being creating this new object with a copy of the mothers arraylist freinds, after setup.

Having looked through and tried to do this with your getters and setters version i find the same problem; how to create a new son with a copy of the mothers arraylist freinds?

your code revised: (revisions in bold)

XMLElement xml;
int mums = 3;
Mother[] mum = new Mother[mums];

for (int i = 0; i < mum.length; i++) {
    family = xml.getChild(i);
    //get family relations
    friend1 = family.getChild(0);
    int mate1 = friend1.getIntAttribute("mate1");
    friend2 = family.getChild(1);
    int mate2 = friend2.getIntAttribute("mate2");

    mum[i] = new Mother(1+i);
    //add friends
    mum[i].addFriend(mate1);
    mum[i].addFriend(mate2);
}
noLoop();
}

void draw() {
for (int i = 0; i < mum.length; i++) {
mum[i].transmit();
}
}

void mousePressed() {
if (mouseButton == LEFT) {
    //remove the friend of one son
    Son son = mum[1].getBoy(1);
    son.removeFriend(3);
}
if (mouseButton == RIGHT) {
    for (int i = 0; i < mum.length; i++) {
      mum[i].giveBirth();
    }
}
redraw();
}

/*.....................................................................*/

int kids = 2;

class Mother {
Daughter girl;
ArrayList boys;
ArrayList friends = new ArrayList();
int ref;
int boyCount = kids;

Mother(int id) {
    girl = new Daughter(id);
    ref = id;
    boys = new ArrayList();
    for (int i = 0; i < kids; i++) {
      boys.add(new Son(id, i+1));
    }
}

void transmit() {
    girl.display();
    for (int i = 0; i < boys.size(); i++) {
      Son maleChild = getBoy(i+1);
      maleChild.display();
    }
}

Son getBoy(int id) {
    if (id < 1 || id > boys.size())                             //what does this line do?
      return null; // or throw exception or return "empty" boy    //what does this line do?
    return (Son) boys.get(id-1);
}

void addFriend(int id) {
    friends.add(id);
    girl.addFriend(id);
    for (int i = 0; i < boys.size(); i++) {
      Son maleChild = getBoy(i+1);
      maleChild.addFriend(id);
    }
}

void removeFriend(int fallenOutWith) {
friends.remove(new Integer(fallenOutWith));
}

void

display() {
println(ref + ": " + "mum's friends" + friends);
}

void giveBirth() {
boys.add(new Son(ref, boyCount++ + 1)) ;
// how to addFreind(id);

}

/*.....................................................................*/

class Daughter {
int id;
ArrayList friends = new ArrayList();

Daughter(int identity) {
id = identity;
}

void addFriend(int id) {
friends.add(id);
}

void removeFriend(int fallenOutWith) {
println(id + ": girl: i've had a fight with friend " + fallenOutWith + "!");
friends.remove(new Integer(fallenOutWith));
}

void display() {
println(id + ": " + "girl's friends" + friends);
}
}

/*.....................................................................*/

class Son {
int id;
int who;
ArrayList friends = new ArrayList();

Son(int identity, int whom) {
id = identity;
who = whom;
}

void addFriend(int id) {
friends.add(id);
}

void removeFriend(int fallenOutWith) {
println(id + ": " + who + ": i've had a fight with friend " + fallenOutWith + "!");
friends.remove(new Integer(fallenOutWith));
}

void display() {
println(id + ": " + who + ": " + "boy's friends" + friends);
}

}

chunkyork..

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

following on..

adding the following to

void giveBirth(); {

boys.add(new Son(ref, boyCount++ + 1)) ;

}

addFreind(ref);

results in an error "The function addFreind(int) does not exist", which i don't understand because it does.

....thought looping through might be a way to access the family freinds and then add but get the same error message.

    for (int i=0; i<mum.length; i++) {
      for (int j=0; j<mum[i].boys.size(); j++) {
        Son son = (Son) mum[i].boys.get(j);
        if ((i == ref-1) && (j == boyCount-1)) {
          println(ref + ", " + boyCount);               //correctly prints out correct son trying to add mums freinds to
          son.addFreind(ref);

        }
      }
    }

on right mouse click this prints out:

1: girl's friends[2, 3]
1: 1: boy's friends[2, 3]
1: 2: boy's friends[2, 3]
1: 3: boy's friends[]
2: girl's friends[1, 3]
2: 1: boy's friends[1, 3]
2: 2: boy's friends[1, 3]
2: 3: boy's friends[]
3: girl's friends[1, 2]
3: 1: boy's friends[1, 2]
3: 2: boy's friends[1, 2]
3: 3: boy's friends[]

son is born/created but freinds list is empty.

can anyone tell me what i am doing wrong please?

thankyou.

PhiLho

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

if (id < 1 || id > boys.size()) //what does this line do?
return null; // or throw exception or return "empty" boy //what does this line do?

These lines where here only to demonstrate one useful feature of getters: it verifies the given indexes are correct.

addFreind(ref); results in an error "The function addFreind(int) does not exist", which i don't understand because it does.

No. I used the correct English Friend instead of your Freind...

Here are the relevant parts of implementing newborns:

void mousePressed() {
if (mouseButton == LEFT) {
//remove the friend of one son
Son son = mum[1].getBoy(mum[1].getBoyNb());
son.removeFriend(3);
}
else if (mouseButton == RIGHT) {
for (int i = 0; i < mum.length; i++) {
mum[i].giveBirth();
}
}
redraw();
}
// In Mother
int getBoyNb()
{
return boys.size();
}
void giveBirth() {
ArrayList inheritedFriends = new ArrayList();
for (int i = 0; i < friends.size(); i++)
{
inheritedFriends.add(friends.get(i));
}
Son newborn = new Son(ref, boys.size() + 1, inheritedFriends);
boys.add(newborn);
}
class Son {
int id;
int who;
ArrayList friends;
Son(int identity, int whom) {
id = identity;
who = whom;
friends = new ArrayList();
}
Son(int identity, int whom, ArrayList fr) {
id = identity;
who = whom;
friends = fr;
}
// Etc.

chunkyork..

Re: how to add or copy an arraylist to the inner class which is an arraylist of objects?

3 years ago

hilarious - typical englishman (bad with languages)

thanks for all your help....with the correct spelling i got it to work in the way i was trying: so at the end of this thread we have 3 different solutions.

first being your setters & getters (see above)

second, your setters and getters with a different giveBirth()

and finally, the way started out trying to do it.

note: i have not gone through and cleaned up spelling! - but code works.

//end;

code: second, your setters and getters with a different giveBirth()

XMLElement xml;
int mums = 3;
Mother[] mum = new Mother[mums];

    mum[i] = new Mother(1+i);
    //add friends
    mum[i].addFriend(mate1);
    mum[i].addFriend(mate2);
}
noLoop();
}

void draw() {
for (int i = 0; i < mum.length; i++) {
mum[i].transmit();
}
}

void mousePressed() {
if (mouseButton == LEFT) {
    //remove the friend of one son
    Son son = mum[1].getBoy(1);
    son.removeFriend(3);
}
if (mouseButton == RIGHT) {
    for (int i = 0; i < mum.length; i++) {
      mum[i].giveBirth();
    }
}
redraw();
}

int kids = 2;

class Mother {
Daughter girl;
ArrayList boys;
ArrayList friends = new ArrayList();
int ref;
int boyCount = kids;

Mother(int id) {
    girl = new Daughter(id);
    ref = id;
    boys = new ArrayList();
    for (int i = 0; i < kids; i++) {
      boys.add(new Son(id, i+1));
    }
}

void transmit() {
    girl.display();
    for (int i = 0; i < boys.size(); i++) {
      Son maleChild = getBoy(i+1);
      maleChild.display();
    }
}

Son getBoy(int id) {
    if (id < 1 || id > boys.size())
      return null; // or throw exception or return "empty" boy
    return (Son) boys.get(id-1);
}

void addFriend(int id) {
    friends.add(id);
    girl.addFriend(id);
    for (int i = 0; i < boys.size(); i++) {
      Son maleChild = getBoy(i+1);
      maleChild.addFriend(id);
    }
}

void removeFriend(int fallenOutWith) {
friends.remove(new Integer(fallenOutWith));
}

void display() {
println(ref + ": " + "mum's friends" + friends);
}

void giveBirth() {
    boys.add(new Son(ref, boyCount++ + 1)) ;
    for (int i=0; i<mum.length; i++) {
      for (int j=0; j<mum[i].boys.size(); j++) {
        Son son = (Son) mum[i].boys.get(j);
        if ((i == ref-1) && (j == boyCount-1)) {
          for (int k=0; k<mum[ref-1].friends.size(); k++) {
            int buddy = (Integer) mum[ref-1].friends.get(k);
            son.addFriend(buddy);
          }
        }
      }
    }
}

}

class Daughter {
int id;
ArrayList friends = new ArrayList();

Daughter(int identity) {
id = identity;
}

void addFriend(int id) {
friends.add(id);
}

void removeFriend(int fallenOutWith) {
println(id + ": girl: i've had a fight with friend " + fallenOutWith + "!");
friends.remove(new Integer(fallenOutWith));
}

void display() {
println(id + ": " + "girl's friends" + friends);
}
}

class Son {
int id;
int who;
ArrayList friends = new ArrayList();

Son(int identity, int whom) {
id = identity;
who = whom;
}

void addFriend(int id) {
friends.add(id);
}

void removeFriend(int fallenOutWith) {
println(id + ": " + who + ": i've had a fight with friend " + fallenOutWith + "!");
friends.remove(new Integer(fallenOutWith));
}

void display() {
println(id + ": " + who + ": " + "boy's friends" + friends);
}

}

code: and finally, the way started out trying to do it.

XMLElement xml;
int mums = 3;
Mother [] mum = new Mother [mums];
public ArrayList familyFreinds;

for (int i=0; i<mum.length; i++) {
    family = xml.getChild(i);
    //get family relations
    freind1 = family.getChild(0);
    int mate1 = freind1.getIntAttribute("mate1");
    freind2 = family.getChild(1);
    int mate2 = freind2.getIntAttribute("mate2");

    mum[i] = new Mother(1+i);
    //add freinds
    mum[i].freinds.add(mate1);
    mum[i].girl.freinds.add(mate1);
    mum[i].freinds.add(mate2);
    mum[i].girl.freinds.add(mate2);
    familyFreinds = new ArrayList();
    familyFreinds.add(mate1);
    familyFreinds.add(mate2);
    for (int j=0; j<mum[i].boys.size(); j++) {
      Son son = (Son) mum[i].boys.get(j);
      son.freinds.add(mate1);
      son.freinds.add(mate2);
    }
}
noLoop();
}

void draw() {
   println("family relations");
   for (int i = 0; i < mum.length; i++) {
    mum[i].transmit();
}
}

void mousePressed() {
if (mouseButton == LEFT) {
    //remove the freind of one son
    for (int i=0; i<mum.length; i++) {
      for (int j=0; j<mum[i].boys.size(); j++) {
        Son son = (Son) mum[i].boys.get(j);
        if ((son.id == 2) && (son.who == 1)) {
          println(son.id + ": " + son.who + ": i've had a fight with freind 3!");
          for (int k=0; i<son.freinds.size(); k++) {
            int fallenOutWith = (Integer) son.freinds.get(k);
            if (fallenOutWith == 3) {
              son.freinds.remove(new Integer(fallenOutWith));
              }
            }
          }
        }
      }
    }
      if (mouseButton == RIGHT) {
    for (int i = 0; i < mum.length; i++) {
      mum[i].giveBirth();
    }
}
    redraw();
}

int kids = 2;

class Mother {
Daughter girl;
ArrayList boys;
ArrayList freinds = new ArrayList();
int ref;
int boyCount = kids;

Mother(int id) {
    girl = new Daughter(id);
    ref = id;
    boys = new ArrayList();
    for (int i=0; i<kids; i++) {
      boys.add(new Son(id, i+1));
    }
}

void transmit() {
   println(ref + ": " + "mums freinds" + freinds);
   girl.display();
   for (int i=0; i<boys.size(); i++) {
     Son maleChild = (Son) boys.get(i);
     maleChild.display();
    }
}

void giveBirth() {
    boys.add(new Son(ref, boyCount++ +1)) ;
    for (int i=0; i<mum.length; i++) {
      for (int j=0; j<mum[i].boys.size(); j++) {
        Son son = (Son) mum[i].boys.get(j);
        if ((i == ref-1) && (j == boyCount-1)) {
          for (int k=0; k<mum[ref-1].freinds.size(); k++) {
            int buddy = (Integer) mum[ref-1].freinds.get(k);
            son.freinds.add(buddy);
          }
        }
      }
    }
}

}

class Daughter {
int id;
ArrayList freinds = new ArrayList();

Daughter(int identity) {
id = identity;
}

void display() {
println(id + ": " + "girls freinds" + freinds);
}

}

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