Deleting a node in a family tree

I'm trying to calclulate the best way to delete a node in a family tree. First, a little description of how the app works.

My app makes the following assumption:

Any node can only have one partner. That means that any child a single node has, it will also be the partner nodes child too. Therefore, step relations, divorces etc aren't compensated for. A node always has two parents - A mother and father cannot be added seperately. If the user doesn't know the details - the nodes attributes are set to a default value.

Also any node can add parents, siblings, children to itself. Therefore in law relationships can be added.

EDIT: After studying Andreas' answer, I have come to realise that my code may need some re-working. I'm trying to add my source but it exceeds the limit of charracters...Any advice?

Here is the FamilyTree Class:

package familytree;

import java.io.PrintStream;
public class FamilyTree {
    private static final int DISPLAY_FAMILY_MEMBERS = 1;
    private static final int ADD_FAMILY_MEMBER = 2;
    private static final int REMOVE_FAMILY_MEMBER = 3;
    private static final int EDIT_FAMILY_MEMBER = 4;
    private static final int SAVE_FAMILY_TREE = 5;
    private static final int LOAD_FAMILY_TREE = 6;
    private static final int DISPLAY_ANCESTORS = 7;
    private static final int DISPLAY_DESCENDANTS = 8;
    private static final int QUIT = 9;
    private Input in;
    private Family family;
    private PrintStream out;

    public FamilyTree(Input in, PrintStream out) {
        this.in = in;
        this.out = out;
        family = new Family();
    }

    public void start() {
        out.println("\nWelcome to the Family Tree Builder");
        initialise();
        while (true) {
            displayFamilyTreeMenu();
            int command = getCommand();
            if (quit(command)) {
                break;
            }
            executeOption(command);
        }
    }

    private int getCommand() {
        return getInteger("\nEnter command: ");
    }

    private int getInteger(String message) {
        while (true) {
            out.print(message);
            if (in.hasNextInt()) {
                int n = in.nextInt();
                in.nextLine();
                return n;
            } else {
                in.nextLine();
                out.println("Your input was not understood. Please try again.");
            }
        }
    }

    //good
    private void displayFamilyTreeMenu() {
        out.println("\nFamily Tree Menu");
        out.println(DISPLAY_FAMILY_MEMBERS + ". Display Family Members");
        out.println(ADD_FAMILY_MEMBER + ". Add Family Member");
        out.println(REMOVE_FAMILY_MEMBER + ". Remove Family Member");
        out.println(EDIT_FAMILY_MEMBER + ". Edit Family Member");
        out.println(SAVE_FAMILY_TREE + ". Save Family Tree");
        out.println(LOAD_FAMILY_TREE + ". Load Family Tree");
        out.println(DISPLAY_ANCESTORS + ". Display Ancestors");
        out.println(DISPLAY_DESCENDANTS + ". Display Descendants");
        out.println(QUIT + ". Quit");
    }

    //good
    private boolean quit(int opt) {
        return (opt == QUIT) ? true : false;
    }

    //good
    private void executeOption(int choice) {
        switch (choice) {
            case DISPLAY_FAMILY_MEMBERS:
                displayFamilyMembers();
                break;
            case ADD_FAMILY_MEMBER:
                addFamilyMember();
                break;
            case REMOVE_FAMILY_MEMBER:
                removeMember();
                break;
            case EDIT_FAMILY_MEMBER:
                editMember();
                break;
            case SAVE_FAMILY_TREE:
                saveFamilyTree();
                break;
            case LOAD_FAMILY_TREE:
                loadFamilyTree();
                break;
            case DISPLAY_ANCESTORS:
                displayAncestors();
                break;
            case DISPLAY_DESCENDANTS:
                displayDescendants();
                break;
            default:
                out.println("Not a valid option! Try again.");
                break;
        }
    }

    private void removeMember() {
        displayFamilyMembers();
        int choice = selectMember();
        if (choice >= 0) {
            FamilyMember f = family.getFamilyMember(choice);
            if (f.getIndex() == 0) {
                out.println("Cannot delete yourself!");
                return;
            }

            deleteMember(f);
        }
    }

    private void deleteMember(FamilyMember f) {
        //remove from tree
        family.removeMember(f);

        //remove all links to this person
        if (f.hasParents()) {
            f.getMother().removeChild(f);
            f.getFather().removeChild(f);
        }
        if(f.getPartner()!=null){
            f.getPartner().setPartner(null);
            f.setPartner(null);
        }

        if (f.hasChildren()) {
            for (FamilyMember member : f.getChildren()) {
                if (f == member.getMother()) {
                    member.setMother(null);
                }
                if (f == member.getFather()) {
                    member.setFather(null);
                }
                if (f == member.getPartner()) {
                    member.setPartner(null);
                }
            }
        }
    }

    private void saveFamilyTree() {
        out.print("Enter file name: ");
        String fileName = in.nextLine();
        FileOutput output = new FileOutput(fileName);
        family.save(output);
        output.close();
        saveRelationships();
    }

    private void saveRelationships() {
        FileOutput output = new FileOutput("Relationships.txt");
        family.saveRelationships(output);
        output.close();
    }

    private void loadFamilyTree() {
        out.print("Enter file name: ");
        String fileName = in.nextLine();
        FileInput input = new FileInput(fileName);
        family.load(input);
        input.close();
        loadRelationships();
    }

    private void loadRelationships() {
        FileInput input = new FileInput("Relationships.txt");
        family.loadRelationships(input);
        input.close();
    }

    //for selecting family member for editing adding nodes etc
    private void displayFamilyMembers() {
        out.println("\nDisplay Family Members");
        int count = 0;
        for (FamilyMember member : family.getFamilyMembers()) {
            out.println();
            if (count + 1 < 10) {
                out.println((count + 1) + ".  " + member.getFirstName() + " " + member.getLastName());
                out.println("    " + member.getGender());
                out.println("    " + member.getDob());
                out.println("    Generation: " + (member.getGeneration() + 1));
            } else {
                out.println((count + 1) + ". " + member.getFirstName() + " " + member.getLastName());
                out.println("    " + member.getGender());
                out.println("    " + member.getDob());
                out.println("    Generation: " + (member.getGeneration() + 1));
            }
            count++;
        }
    }

    private int selectRelative() {
        out.println("\nSelect Relative");
        out.println("1. Add Parents");
        out.println("2. Add Child");
        out.println("3. Add Partner");
        out.println("4. Add Sibling");
        //out.print("\nEnter Choice: ");
        //int choice = in.nextInt();
        int choice = getInteger("\nEnter Choice: ");
        if (choice > 0 && choice < 5) {
            return choice;
        }
        return (-1);
    }

    private void addFamilyMember() {
        if (family.getFamilyMembers().isEmpty()) {
            out.println("No Members To Add To");
            return;
        }
        int memberIndex = selectMember();
        if (memberIndex >= 0) {
            FamilyMember member = family.getFamilyMember(memberIndex);
            int relative = selectRelative();
            if (relative > 0) {
                out.println("\nAdd Member");
                //if choice is valid
                switch (relative) {
                    case 1:
                        //adding parents
                        FamilyMember mum, dad;
                        if (!member.hasParents()) {
                            out.println("Enter Mothers Details");
                            mum = addMember(relative, "Female");
                            out.println("\nEnter Fathers Details");
                            dad = addMember(relative, "Male");
                            member.linkParent(mum);
                            member.linkParent(dad);
                            mum.linkPartner(dad);
                            mum.setGeneration(member.getGeneration() - 1);
                            dad.setGeneration(member.getGeneration() - 1);
                            sortGenerations();
                        } else {
                            out.println(member.getFirstName() + " " + member.getLastName() + " already has parents.");
                        }
                        break;
                    case 2:
                        //adding child
                        if (member.getPartner() == null) {
                            FamilyMember partner;
                            if (member.getGender().equals("Male")) {
                                out.println("Enter Mothers Details");
                                partner = addMember(1, "Female");
                            } else {
                                out.println("Enter Fathers Details");
                                partner = addMember(1, "Male");
                            }
                            //create partner
                            member.linkPartner(partner);
                            partner.setGeneration(member.getGeneration());
                            out.println();
                        }
                        out.println("Enter Childs Details");
                        FamilyMember child = addMember(relative, "");
                        child.linkParent(member);
                        child.linkParent(member.getPartner());
                        child.setGeneration(member.getGeneration() + 1);
                        sortGenerations();
                        break;
                    case 3:
                        //adding partner
                        if (member.getPartner() == null) {
                            out.println("Enter Partners Details");
                            FamilyMember partner = addMember(relative, "");
                            member.linkPartner(partner);
                            partner.setGeneration(member.getGeneration());
                        } else {
                            out.println(member.getFirstName() + " " + member.getLastName() + " already has a partner.");
                        }
                        break;
                    case 4:
                        //adding sibling
                        if (member.getFather() == null) {
                            out.println("Enter Mothers Details");
                            mum = addMember(1, "Female");
                            out.println("\nEnter Fathers Details");
                            dad = addMember(1, "Male");
                            member.linkParent(mum);
                            member.linkParent(dad);
                            mum.linkPartner(dad);
                            mum.setGeneration(member.getGeneration() - 1);
                            dad.setGeneration(member.getGeneration() - 1);
                            sortGenerations();
                            out.println("\nEnter Siblings Details");
                        } else {
                            out.println("Enter Siblings Details");
                        }
                        FamilyMember sibling = addMember(relative, "");

                        //create mum and dad
                        mum = member.getMother();
                        dad = member.getFather();
                        sibling.linkParent(mum);
                        sibling.linkParent(dad);
                        sibling.setGeneration(member.getGeneration());
                        break;
                }
            } else {
                out.println("Invalid Option!");
            }
        } else {
            out.println("Invalid Option!");
        }
    }

    private int selectMember() {
        displayFamilyMembers();
        //out.print("\nSelect Member: ");
        //int choice = in.nextInt();
        int choice = getInteger("\nSelect Member: ");
        if (choice > 0 && choice <= family.getFamilyMembers().size()) {
            return (choice - 1);
        }
        return -1;
    }

    private void editMember() {
        int choice = selectMember();
        if (choice >= 0) {
            out.println("Select Detail To Edit: ");
            out.println("1. Name");
            out.println("2. Gender");
            out.println("3. Date of Birth");
            //out.print("\nEnter Choice: ");
            //int opt = in.nextInt();
            int opt = getInteger("\nEnter Choice: ");
            if (opt > 0 && opt < 4) {
                switch (opt) {
                    case 1: //name
                        out.print("Enter New First Name: ");
                        String fName = in.nextLine();
                        out.print("Enter New Last Name: ");
                        String lName = in.nextLine();
    开发者_JS百科                    family.changeName(fName, lName, choice);
                        break;
                    case 2: //Gender
                        FamilyMember f = family.getFamilyMember(choice);
                        String gender = f.getGender();
                        if (f.getChildren().isEmpty()) {
                            gender = selectGender();
                            family.changeGender(gender, choice);
                        } else {
                            //swap genders
                            //swap mother father relationships for kids
                            swapGenders(f, choice);
                        }
                        break;
                    case 3:
                        String dob = enterDateOfBirth();
                        family.changeDOB(dob, choice);
                }
            } else {
                out.println("Invalid Choice!");
            }
        }

    }

    private FamilyMember addMember(int option, String gender) {
        out.print("Enter First Name: ");
        String fName = formatString(in.nextLine().trim());
        out.print("Enter Last Name: ");
        String lName = formatString(in.nextLine().trim());
        //String gender;
        if (option != 1) { //if not adding parents
            gender = selectGender();
        }
        String dob = enterDateOfBirth();
        FamilyMember f = family.getFamilyMember(family.addMember(fName, lName, gender, dob));
        f.setIndex(family.getFamilyMembers().size() - 1);
        return (f);
    }

    private String selectGender() {
        String gender = null;
        out.println("Select Gender");
        out.println("1. Male");
        out.println("2. Female");
        //out.print("Enter Choice: ");
        //int gOpt = in.nextInt();
        int gOpt = getInteger("Enter Choice: ");
        if (gOpt == 1) {
            gender = "Male";
        } else if (gOpt == 2) {
            gender = "Female";
        } else {
            out.println("Invalid Choice");
        }
        return gender;
    }

    private void swapGenders(FamilyMember f, int choice) {
        String gender;
        out.println("\nNOTE: Editing A Parent Nodes Gender Will Swap Parents Genders\n"
                + "And Swap Mother/Father Relationships For All Children.");
        out.println("\nContinue:");
        out.println("1. Yes");
        out.println("2. No");
        //out.print("\nEnter Choice: ");
        //int select = in.nextInt();
        int select = getInteger("\nEnter Choice: ");
        if (select > 0 && select < 3) {
            switch (select) {
                case 1:
                    //swap relationships
                    gender = selectGender();
                    //if selected gender is different
                    if (!gender.equals(f.getGender())) {
                        //swap
                        String g = f.getGender();
                        family.changeGender(gender, choice);
                        family.changeGender(g, f.getPartner().getIndex());
                        if (g.equals("Male")) {
                            for (FamilyMember m : f.getChildren()) {
                                m.setMother(f);
                                m.setFather(f.getPartner());
                            }
                        } else {
                            for (FamilyMember m : f.getChildren()) {
                                m.setFather(f);
                                m.setMother(f.getPartner());
                            }
                        }
                    }
                    break;
                case 2:
                    break;
            }
        } else {
            out.println("Invalid Choice");
        }
    }

    private String formatString(String s) {
        String firstLetter = s.substring(0, 1);
        String remainingLetters = s.substring(1, s.length());
        s = firstLetter.toUpperCase() + remainingLetters.toLowerCase();
        return s;
    }

    private String enterDateOfBirth() {
        out.print("Enter Year Of Birth (0 - 2011): ");
        String y = in.nextLine();

        out.print("Enter Month Of Birth (1-12): ");
        String m = in.nextLine();
        if (m.trim().equals("")) {
            m = "0";
        }
        if (Integer.parseInt(m) < 10) {
            m = "0" + m;
        }
        m += "-";

        out.print("Enter Date of Birth (1-31): ");
        String d = in.nextLine();

        if (d.trim().equals("")) {
            d = "0";
        }
        if (Integer.parseInt(d) < 10) {
            d = "0" + d;
        }
        d += "-";

        String dob = d + m + y;
        while (!DateValidator.isValid(dob)) {
            out.println("Invalid Date. Try Again:");
            dob = enterDateOfBirth();
        }
        return (dob);
    }

    private void displayAncestors() {
        out.print("\nDisplay Ancestors For Which Member: ");
        int choice = selectMember();
        if (choice >= 0) {
            FamilyMember node = family.getFamilyMember(choice);
            FamilyMember ms = findRootNode(node, 0, 2, -1);
            FamilyMember fs = findRootNode(node, 1, 2, -1);
            out.println("\nPrint Ancestors");
            out.println("\nMothers Side");
            if(ms==null){
                out.println("Member has no mother");
            }else{
                printDescendants(ms, node, ms.getGeneration());
            }
            out.println("\nFathers Side");
            if(fs==null){
                out.println("Member has no father");
            }else{
                printDescendants(fs, node, fs.getGeneration());
            }
        } else {
            out.println("Invalid Option!");
        }
    }

    private void displayDescendants() {
        out.print("\nDisplay Descendants For Which Member: ");
        int choice = selectMember();
        if (choice >= 0) {
            FamilyMember node = family.getFamilyMember(choice);
            out.println("\nPrint Descendants");
            printDescendants(node, null, 0);
        } else {
            out.println("Invalid Option!");
        }
    }

    private FamilyMember findRootNode(FamilyMember node, int parent, int numGenerations, int count) {
        FamilyMember root;
        count++;
        if (count < numGenerations) {
            if (parent == 0) {
                if(node.hasMother()){
                    node = node.getMother();
                }else{
                    return node;
                }
            } else {
                if(node.hasFather()){
                    node = node.getFather();
                }else{
                    return node;
                }
            }
            root = findRootNode(node, 1, numGenerations, count);
            return root;
        }

        return node;
    }

    private int findHighestLeafGeneration(FamilyMember node) {
        int gen = node.getGeneration();
        for (int i = 0; i < node.getChildren().size(); i++) {
            int highestChild = findHighestLeafGeneration(node.getChild(i));
            if (highestChild > gen) {
                gen = highestChild;
            }
        }
        return gen;
    }

    private void printDescendants(FamilyMember root, FamilyMember node, int gen) {
        out.print((root.getGeneration() + 1) + " " + root.getFullName());
        out.print(" [" + root.getDob() + "] ");
        if (root.getPartner() != null) {
            out.print("+Partner: " + root.getPartner().getFullName() + " [" + root.getPartner().getDob() + "] ");
        }
        if (root == node) {
            out.print("*");
        }
        out.println();

        if (!root.getChildren().isEmpty() && root != node) {
            for (int i = 0; i < root.getChildren().size(); i++) {
                for (int j = 0; j < root.getChild(i).getGeneration() - gen; j++) {
                    out.print("  ");
                }
                printDescendants(root.getChild(i), node, gen);
            }
        } else {
            return;
        }
    }

    //retrieve highest generation
    public int getRootGeneration() {
        int min = family.getFamilyMember(0).getGeneration();
        for (int i = 0; i < family.getFamilyMembers().size(); i++) {
            min = Math.min(min, family.getFamilyMember(i).getGeneration());
        }
        return Math.abs(min);
    }

    public void sortGenerations() {
        int amount = getRootGeneration();
        for (FamilyMember member : family.getFamilyMembers()) {
            member.setGeneration(member.getGeneration() + amount);
        }
    }

    //test method - temporary
    private void initialise() {
        family.addMember("Bart", "Simpson", "Male", "18-03-1985");
        family.getFamilyMember(0).setIndex(0);
        family.addMember("Homer", "Simpson", "Male", "24-09-1957");
        family.getFamilyMember(1).setIndex(1);
        family.addMember("Marge", "Simpson", "Female", "20-07-1960");
        family.getFamilyMember(2).setIndex(2);
        family.addMember("Lisa", "Simpson", "Female", "28-01-1991");
        family.getFamilyMember(3).setIndex(3);
        family.addMember("Abe", "Simpson", "Male", "10-03-1920");
        family.getFamilyMember(4).setIndex(4);
        family.addMember("Mona", "Simpson", "Female", "18-09-1921");
        family.getFamilyMember(5).setIndex(5);


        //set relationships
        family.getFamilyMember(0).setMother(family.getFamilyMember(2));
        family.getFamilyMember(0).setFather(family.getFamilyMember(1));
        family.getFamilyMember(3).setMother(family.getFamilyMember(2));
        family.getFamilyMember(3).setFather(family.getFamilyMember(1));


        family.getFamilyMember(1).addChild(family.getFamilyMember(3));
        family.getFamilyMember(1).addChild(family.getFamilyMember(0));

        family.getFamilyMember(2).addChild(family.getFamilyMember(3));
        family.getFamilyMember(2).addChild(family.getFamilyMember(0));

        family.getFamilyMember(1).setPartner(family.getFamilyMember(2));
        family.getFamilyMember(2).setPartner(family.getFamilyMember(1));

        family.getFamilyMember(4).setPartner(family.getFamilyMember(5));
        family.getFamilyMember(5).setPartner(family.getFamilyMember(4));

        family.getFamilyMember(1).setMother(family.getFamilyMember(5));
        family.getFamilyMember(1).setFather(family.getFamilyMember(4));

        family.getFamilyMember(4).addChild(family.getFamilyMember(1));
        family.getFamilyMember(5).addChild(family.getFamilyMember(1));

        family.getFamilyMember(0).setGeneration(2);
        family.getFamilyMember(1).setGeneration(1);
        family.getFamilyMember(2).setGeneration(1);
        family.getFamilyMember(3).setGeneration(2);
        family.getFamilyMember(4).setGeneration(0);
        family.getFamilyMember(5).setGeneration(0);
    }
}

All tasks require the same effort. It will always go like this:

public void deleteFamilyMember(FamilyMember member) {
  member.mother.children.remove(member);
  member.father.children.remove(member);
  member.partner.children.remove(member);
  for (FamilyMember child:children) {
    if (child.father == member) child.father = null;
    if (child.mother == member) child.mother = null;
    if (child.partner == member) child.partner = null;
  }
  // now all references to this member are eliminated, gc will do the rest.
}

Example:

Homer.mother = ??
Homer.father = ??
Homer.partner = Marge
Homer.children = {Bart, Lisa, Maggie}

Marge.mother = ??
Marge.father = ??
Marge.partner = Homer
Marge.children = {Bart, Lisa, Maggie}

Bart.mother = Marge
Bart.father = Homer
Bart.partner = null
Bart.children = {}

Lisa.mother = Marge
Lisa.father = Homer
Lisa.partner = null
Lisa.children = {}

Maggie.mother = Marge
Maggie.father = Homer
Maggie.partner = null
Maggie.children = {}

To remove Bart from the familiy tree, we should set Bart's mother and father attribute to null and need to remove Bart from Homer's and Marge's list of children.

To remove Marge, we have to set her partner's partner to null (Homer.partner) and visit all children to clear their mother attribute (that's this child.mother part of the code above)

I would model things differently and do the work in the FamilyMember class. Here's a sample implementation:

public class FamilyMember{

    public enum Gender{
        MALE, FEMALE
    }

    private final Set<FamilyMember> exPartners =
        new LinkedHashSet<FamilyMember>();

    public Set<FamilyMember> getExPartners(){
        return new LinkedHashSet<FamilyMember>(exPartners);
    }

    public FamilyMember getFather(){
        return father;
    }

    public FamilyMember getMother(){
        return mother;
    }

    public Set<FamilyMember> getSiblings(){
        final Set<FamilyMember> set =
            father == null && mother == null ? Collections
                .<FamilyMember> emptySet() : new HashSet<FamilyMember>();
        if(father != null){
            set.addAll(father.children);
        }
        if(mother != null){
            set.addAll(mother.children);
        }
        set.remove(this);
        return set;
    }

    public String getName(){
        return name;
    }

    private final Gender gender;
    private FamilyMember partner;
    private final FamilyMember father;
    private final FamilyMember mother;
    private final Set<FamilyMember> children =
        new LinkedHashSet<FamilyMember>();
    private final String name;

    public FamilyMember haveChild(final String name, final Gender gender){
        if(partner == null){
            throw new IllegalStateException("Partner needed");
        }
        final FamilyMember father = gender == Gender.MALE ? this : partner;
        final FamilyMember mother = father == this ? partner : this;
        return new FamilyMember(father, mother, name, gender);
    }

    public Set<FamilyMember> getChildren(){
        return new LinkedHashSet<FamilyMember>(children);
    }

    @Override
    public String toString(){

        return "[" + name + ", " + gender + "]";
    }

    public FamilyMember(final String name, final Gender gender){
        this(null, null, name, gender);
    }

    public FamilyMember(final FamilyMember father,
        final FamilyMember mother,
        final String name,
        final Gender gender){
        if(name == null){
            throw new IllegalArgumentException("A kid needs a name!");
        }
        if(gender == null){
            throw new IllegalArgumentException("Which is it going to be?");
        }
        this.father = father;
        this.name = name;
        this.gender = gender;
        if(father != null){
            father.children.add(this);
        }
        this.mother = mother;
        if(mother != null){
            mother.children.add(this);
        }
    }

    public FamilyMember hookUpWith(final FamilyMember partner){
        if(partner.gender == gender){
            throw new IllegalArgumentException(
                "Sorry, same-sex-marriage would make things too complicated");
        }
        this.partner = partner;
        partner.partner = this;
        return this;
    }

    public FamilyMember splitUp(){
        if(partner == null){
            throw new IllegalArgumentException("Hey, I don't have a partner");
        } else{
            partner.partner = null;
            exPartners.add(partner);
            partner.exPartners.add(this);
            partner = null;
        }
        return this;
    }

    public FamilyMember getPartner(){
        return partner;
    }

}

And here's the much more expressive code you can write that way:

FamilyMember marge = new FamilyMember("Marge", Gender.FEMALE);
FamilyMember homer = new FamilyMember("Homer", Gender.MALE);
homer.hookUpWith(marge);
FamilyMember bart = homer.haveChild("Bart", Gender.MALE);
FamilyMember lisa = marge.haveChild("Lisa", Gender.FEMALE);
System.out.println("Homer & Marge: " + marge + ", "
    + marge.getPartner());
homer.splitUp();
FamilyMember dolores =
    marge
      .hookUpWith(new FamilyMember("New Guy", Gender.MALE))
      .haveChild("Dolores", Gender.FEMALE);
FamilyMember bruno =
    homer
      .hookUpWith(new FamilyMember("New Girl", Gender.FEMALE))
      .haveChild("Bruno", Gender.MALE);

System.out.println(
    "Marge & Partner: " + marge + ", " + marge.getPartner());
System.out.println("Marge's Ex-Partners: " + marge.getExPartners());
System.out.println(
    "Homer & Partner: " + homer + ", " + homer.getPartner());
System.out.println("Homer's Ex-Partners: " + homer.getExPartners());
System.out.println("Marge's kids: " + marge.getChildren());
System.out.println("Homer's kids: " + homer.getChildren());
System.out.println("Dolores's siblings: " + dolores.getSiblings());
System.out.println("Brunos's siblings: " + bruno.getSiblings());

Output:

Homer & Marge: [Marge, FEMALE], [Homer, MALE]
Marge & Partner: [Marge, FEMALE], [New Guy, MALE]
Marge's Ex-Partners: [[Homer, MALE]]
Homer & Partner: [Homer, MALE], [New Girl, FEMALE]
Homer's Ex-Partners: [[Marge, FEMALE]]
Marge's kids: [[Bart, MALE], [Lisa, FEMALE], [Dolores, FEMALE]]
Homer's kids: [[Bart, MALE], [Lisa, FEMALE], [Bruno, MALE]]
Dolores's siblings: [[Bart, MALE], [Lisa, FEMALE]]
Brunos's siblings: [[Bart, MALE], [Lisa, FEMALE]]