Question

I need to create new warrior, assign name, and get his description with function specified in GameCahracter class. When I am trying to run – it stops on weapon.type ; // <<Exception showing that weapon=null. Why? As far as I know warrior constructor assigned to variable weapon a link to new Weapon.Sword. Then using variable weapon I should be able to access it’s field type. What is wrong here?

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abstract class GameCahracter{
    public String name;
    public String type;
    public Weapon weapon; 
    public int hitPoints;

    public String getDescription(){
        return  name + "; " + 
        type + "; "  + 
        hitPoints + " hp; " + 

        weapon.type ; // << Exception
    }

    public static class Warrior extends Player{
        public Warrior() {
            type = "Warrior";
            hitPoints = 100;
            Weapon.Sword weapon = new Weapon.Sword(); 
    }
}

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abstract class Player extends GameCahracter {

}

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 abstract class Weapon {
    public int damage;
    public String type = "default";

    public int getDamage(){
        return this.damage;
    }

    public static class Sword extends Weapon{

        public Sword() {

            String type = "Sword";
            int damage = 10; 
        }

    }
}

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GameCahracter.Warrior wr = new GameCahracter.Warrior();     
wr.setName("Joe");
System.out.println( wr.getDescription());

---

EDIT1

For some reason I’m having default string when printing out weapon.type. Why? How can I get typeto be Sword?

Answer 1

In this moment your constructor leave weapon field to null. Simply creates a Sword instance that is garbaged once is out of the scope.

So change the line

Weapon.Sword weapon = new Weapon.Sword(); 

in your Warrior constructor with

weapon = new Weapon.Sword(); 

or better with

this.weapon = new Weapon.Sword(); 

and you do a similar error in Sword constructor when you write

String type = "Sword";
int damage = 10; 

change them with

this.type = "Sword";
this.damage = 10;