CODEWITHSUNDEEP
javaarraylistrandomcomparisoncomparable
user5840106
user5840106

Reputation:

How to Pair Up Random Indices of an ArrayList with each other

I am currently working on a project where I read in a CSV file that contains a list of Pokemon, as well as their traits. I am trying to run a battle simulator that randomly pairs up these Pokemon with each other and compares their combatScore, which is a result of a simple calculation using their traits such as speed, attack, defense, etc. I read in all of the Pokemon from the CSV file into an ArrayList of type Pokemon. Now, I want to randomly pair them up with each other and compare their combatScore; whoever has the higher score moves on to the next round, and the loser is placed into another ArrayList of defeated Pokemon. However, I do not know how to randomly pair up the Pokemon. Here is my code of the main class so far: 

import java.io.*;
import java.util.ArrayList;
import java.util.Random;

public class assign1 {

public static void main(String[] args) throws IOException {

    String csvFile = args[0];   //path to CSV file
    String writeFile = args[1]; //name of output file that contains list of Pokemon and their traits
    BufferedReader br = null;
    String line = "";
    String cvsSplitBy = ",";

    ArrayList<Pokemon> population = new ArrayList<Pokemon>();

    FileWriter fileWriter = new FileWriter(writeFile);

    BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);

    try {

        br = new BufferedReader(new FileReader(csvFile));
        String headerLine = br.readLine(); // used to read first line of CSV file that contains headers
        while ((line = br.readLine()) != null) {

            Pokemon creature = new Pokemon();
            // use comma as separator
            String[] pokemon = line.split(cvsSplitBy);

            creature.setId(pokemon[0]);
            creature.setName(pokemon[1]);
            creature.setType1(pokemon[2]);
            creature.setType2(pokemon[3]);
            creature.setTotal(pokemon[4]);
            creature.setHp(Integer.parseInt(pokemon[5]));
            creature.setAttack(Integer.parseInt(pokemon[6]));
            creature.setDefense(Integer.parseInt(pokemon[7]));
            creature.setSpAtk(Integer.parseInt(pokemon[8]));
            creature.setSpDef(Integer.parseInt(pokemon[9]));
            creature.setSpeed(Integer.parseInt(pokemon[10]));
            creature.setGeneration(Integer.parseInt(pokemon[11]));
            creature.setLegendary(Boolean.parseBoolean(pokemon[12]));
            creature.getCombatScore();

            // Adds individual Pokemon to the population ArrayList
            population.add(creature);

            // Writes to pokemon.txt the list of creatures
            bufferedWriter.write(creature.getId() + ". "
                    + "Name: " + creature.getName() + ": "
                    + "Type 1: " + creature.getType1() + ", "
                    + "Type 2: " + creature.getType2() + ", "
                    + "Total: " + creature.getTotal() + ", "
                    + "HP: " + creature.getHp() + ", "
                    + "Attack: " + creature.getAttack() + ", "
                    + "Defense: " + creature.getDefense() + ", "
                    + "Special Attack: " + creature.getSpAtk() + ", "
                    + "Special Defense: " + creature.getSpDef() + ", "
                    + "Speed: " + creature.getSpeed() + ", "
                    + "Generation: " + creature.getGeneration() + ", "
                    + "Legendary? " + creature.isLegendary() + ", "
                    + "Score: " + creature.getCombatScore());
            bufferedWriter.newLine();

        }

    }
    catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    catch (IOException e) {
        e.printStackTrace();
    }
    finally {
        if (br != null) {
            try {
                br.close();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    bufferedWriter.close();

}
}

And here is the code for my Pokemon class:

public class Pokemon {
String id;
String name;
String type1;
String type2;
String total;
int hp;
int attack;
int defense;
int spAtk;
int spDef;
int speed;
int generation;
boolean legendary;


public Pokemon() {}

public String getId () {
        return id;
    }

public void setId(String id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getType1() {
    return type1;
}

public void setType1(String type1) {
    this.type1 = type1;
}

public String getType2() {
    return type2;
}

public void setType2(String type2) {
    this.type2 = type2;
}

public String getTotal() {
    return total;
}

public void setTotal(String total) {
    this.total = total;
}

public int getHp() {
    return hp;
}

public void setHp(int hp) {
    this.hp = hp;
}

public int getAttack() {
    return attack;
}

public void setAttack(int attack) {
    this.attack = attack;
}

public int getDefense() {
    return defense;
}

public void setDefense(int defense) {
    this.defense = defense;
}

public int getSpAtk() {
    return spAtk;
}

public void setSpAtk(int spAtk) {
    this.spAtk = spAtk;
}

public int getSpDef() {
    return spDef;
}

public void setSpDef(int spDef) {
    this.spDef = spDef;
}

public int getSpeed() {
    return speed;
}

public void setSpeed(int speed) {
    this.speed = speed;
}

public int getGeneration() {
    return generation;
}

public void setGeneration(int generation) {
    this.generation = generation;
}

public boolean isLegendary() {
    return legendary;
}

public void setLegendary(boolean legendary) {
    this.legendary = legendary;
}

public int getCombatScore() {
    return (speed/2) * (attack + (spAtk/2)) + (defense + (spDef/2));
}

@Override
public String toString() {
    return "Name: " + this.getName()
            + ", Type 1: " + this.getType1()
            + ", Type 2: " + this.getType2()
            + ", Total: " + this.getTotal()
            + ", HP: " + this.getHp()
            + ", Attack: " + this.getAttack()
            + ", Defense: " + this.getDefense()
            + ", Sp. Attack: " + this.getSpAtk()
            + ", Sp. Defense: " + this.getSpDef()
            + ", Generation: " + this.getGeneration()
            + ", Legnedary: " + this.isLegendary()
            + ", Score: " + this.getCombatScore();
}
}

I only want to compare their combatScore values to each other. Any help/suggestions would be much appreciated.

Upvotes: 0

Views: 881

Answers (2)

Zamrony P. Juhara
Zamrony P. Juhara

Reputation: 5262

What come to my mind is this. You pick one random item (pokemon) from array list. Remove it from array list. Then you pick one random item again and remove it. Now you have a pair of items. Repeat above step for remaining items in array list until no more items available.

Or you can shuffle whole array list first and then pick item i and item i+1 as pair for i=0,2,4,6,...

Collections.shuffle(pokemonsArrayList);
for (int i=0; i< pokemonsArrayList.size(); i+=2) {
     pokemon1 = pokemonsArrayList.get(i);
     pokemon2 = pokemonsArrayList.get(i+1);
}

Just make sure that number of elements in ArrayList is even. Otherwise code above will throw exception index out of bound

Upvotes: 1

matejetz
matejetz

Reputation: 520

Since every element in an ArrayList has an index, you can just get a random element from it by calling

Pokemon pokemon1;
Pokemon pokemon2;
pokemon1 = arrayList.get(Math.random()*arrayList.size());
do {
    pokemon2 = arrayList.get(Math.random()*arrayList.size());
} while(pokemon1.getId() == pokemon2.getId());

then compare the Pokémon you got out of List1 with the one you got from List2.

You can then of course remove the Pokémon from the List if you wish.

Hope that helps you out!

Upvotes: 0

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