How to use an instance variable of one object on another object java

Question

I am making a simple game. When I call the fight method the damage received by the character when it is hit is its own damage variable For example Knight- Health: 100 Damage: 20

Soldier- health: 100 Damage: 10

when I call my method an the knight attacks the soldier and the soldier attacks the knight their health is as follows

Knight-> 80 Health Soldier-> 90 Health

when it should be the other way round

example code

public abstract class BasicCharacter 
{
private double health;
private double damage;
private double attackProbability;
private String name;


public BasicCharacter(double hp,double attp,double d, String n)
{   
    health=hp;
    attackProbability=attp;
    damage=d;
    name=n; 


}


public void setHealth(double hp)
{  
    health=hp;
}

public double getHealth()
{
    return health;
}



public double getDamage()
{
    return damage;
}




public void fight()
{


    double prob=Math.random();

    if(prob<attackProbability)
    {
        JOptionPane.showMessageDialog(null, name+" attacked for " + damage+    "\n" + name + " health " + health +" left");
        health=health-damage;
    }
    else {

        JOptionPane.showMessageDialog(null, name + " missed");
    }


}
}

both the soldiers and the knight are subclasses of BasicCharacter

  public class soldier extends BasicCharacter{} 

thanks

Answer 1

It is because in your fight() method, you are deducting the health from the object's own damage:

health=health-damage;

What you actually wants is probably:

fight(BasicCharacter target){
    target.setHealth(target.getHealth() - this.damage);
}

You can add an argument to your fight method which indicates the fighting target.

Answer 2

Example: Knight attacking Soldier

A simple method that will handle the damaging, send in object you want to damage and the amount of damage.

public void damaging(Object object, Double damage){
 if(object instanceof Soldier){
 ((Soldier)object).setHealth(((Soldier)object).getHealth()-damage);
 }
}