Problem with adjusting health in Pokemon class

Question

I have two classes called Pokemon.java and Move.java which contain methods for creating and modifying Pokemon and their moves. I've created all of the required methods, but I'm having trouble with the attack method, which is supposed to subtract an opponent's health when it's attacked.

Here is the code for the Pokemon.java class:

import java.util.ArrayList;
public class Pokemon
{
    // Copy over your code for the Pokemon class here
    // Private constants
    private static final int MAX_HEALTH = 100;
    private static final int MAX_MOVES = 4;
    private String name;
    private int health;
    private int opponentHealth;
    public static int numMovesForPokemon = Move.getNumOfMoves();
    private Move move;
    private static ArrayList<Move> moveListForPokemon = new ArrayList<Move>();
    private String pokemonImage;

    // Write your Pokemon class here
    public Pokemon(String theName, int theHealth)
    {
        name = theName;
        if(theHealth <= MAX_HEALTH)
        {
            health = theHealth;
        }
    }

    public Pokemon(String name, String image)
    {
        this.name = name;
        health = 100;
        pokemonImage = image;
    }

    public Pokemon(String theName)
    {
        name = theName;
    }    

    public void setImage(String image)
    {
        pokemonImage = image;
    }

    public String getImage()
    {
        return pokemonImage;
    }

    public String getName()
    {
        return name;
    }

    public int getHealth()
    {
        return health;
    }

    public boolean hasFainted()
    {
        if(health <= 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean canLearnMoreMoves()
    {
        if(numMovesForPokemon < 4)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean learnMove(Move other)
    {
        if(canLearnMoreMoves())
        {
            moveListForPokemon = Move.getList();
            moveListForPokemon.add(other);
            numMovesForPokemon++;
            return true;
        }
        else
        {
            return false;
        }
    }

    public void forgetMove(Move other)
    {
            moveListForPokemon.remove(other);
    }

    public static ArrayList<Move> displayList()
    {
        return moveListForPokemon;
    }

    public boolean knowsMove(Move move)
    {
        if(moveListForPokemon.contains(move))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean knowsMove(String moveName)
    {
        if(moveListForPokemon.contains(move.getName()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean attack(Pokemon opponent, Move move)
    {
        if(knowsMove(move))
        {
            opponentHealth = opponent.getHealth();
            opponentHealth -= move.getDamage();
            return true;
        }
        else
        {
            return false;
        }
    }

    public boolean attack(Pokemon opponent, String moveName)
    {
        if(knowsMove(moveName))
        {
            opponentHealth = opponent.getHealth();
            opponentHealth -= move.getDamage();
            return true;
        }
        else
        {
            return false;
        }
    }    

    public String toString()
    {
        return pokemonImage + "\n" + name + " (Health: " + health + " / " + MAX_HEALTH + ")";
    }
    // Add the methods specified in the exercise description
}

Here is the code for the Move.java class:

import java.util.ArrayList;
public class Move
{
    // Copy over your code for the Move class here
    private static final int MAX_DAMAGE = 25;
    private String name;
    private int damage;
    public static int numMoves;
    private static ArrayList<Move> moveList = new ArrayList<Move>();

    public Move(String theName, int theDamage)
    {
        name = theName;
        if(theDamage <= MAX_DAMAGE)
        {
            damage = theDamage;
        }
    }

    public String getName()
    {
        return name;
    }

    public int getDamage()
    {
        return damage;
    }

    public static int getNumOfMoves()
    {
        return numMoves;
    }

    public static ArrayList<Move> getList()
    {
        return moveList;
    }    

    public String toString()
    {
        return name + " (" + damage + " damage)";
    }    
    // Add an equals method so we can compare Moves against each other

    public boolean equals(Move other)
    {
        if(name.equals(other.getName()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }     
}

Finally, here is the code for PokemonTester.java where I test out the methods:

public class PokemonTester extends ConsoleProgram
{
    private PokemonImages images = new PokemonImages();
    public void run()
    {
        // Test out your Pokemon class here!
        Pokemon p1 = new Pokemon("Charrizard", 100);
        Pokemon p2 = new Pokemon("Pikachu", 100);
        Move m1 = new Move("Flamethrower", 20);
        Move m2 = new Move("Fire Breath", 15);
        p1.learnMove(m1);
        System.out.println(p1.knowsMove(m1));
        System.out.println(p1.knowsMove("Flamethrower"));
        System.out.println(p1.attack(p2, m1));
        System.out.println(p2.getHealth());
    }
}

Answer 1

You are first assigning the value of Oponent.getHealth() to the int variable oponentHealth which you then modify, however this modification does not affect the health of Opponent but instead just the oponentHealth variable, you either have to directly access and modify the health field of Opponent or implement some kind of setHealth(int health) method in the class Pokemon

Answer 2

I suppose your problem is this:

opponentHealth = opponent.getHealth();
opponentHealth -= move.getDamage();

This code has several problems:

• I'd suggest using a local variable for opponentHealth instead of a class level field
• The opponent doesn't gets to know that it's health was subtracted. You have to share this knowledge with him, e.g. by introducing a setter for health and then calling opponent.setHealth(opponentHealth)