Passing variables through classes?

[EternalFacepalm]

My problem is quite simple, yet I haven't found any ways of doing this as of this moment.
I need to get the integer "playerHP" working in a subclass. For example, I'm creating a class for all the items my text RPG needs, yet I need them to have an effect on the initial battle. This would mean that they'd for example heal the player. How do I bring the variable from the initial main to the subclass?

[Iron Lion]

It would make it a lot easier to help you if you posted some code.

[EternalFacepalm]

There isn't very much code displaying what I've tried to do, and the rest of the code doesn't refer to it very much, as I've had problems knowing where to start. Also, I need this for a text RPG I'm making.

What I do have of code to display, though, is this:

if (atkordfs.equals("drink potion")){
		        items itemsObject = new items();
			itemsObject.Potion();

Where atkordfs is a string that's used to execute commands, items is a class, and Potion is a public void that executes a heal.

public class items {
                public void Potion(){
	             System.out.print("You drink the potion, healing 50 HP");
		     trainerHP += 50;

Where trainerHP is the HP of the player.
What my problem is, is basically to transfer trainerHP from the main to the Items-class.

[kjkrum]

It sounds like you're at an early stage of development. It might be a good time to rethink your object design. Objects should model the real-world objects they represent. That means they should contain the data that represents their characteristics, and provide methods that represent actions they could perform, or have performed on them.

I'd create a class that represents your player, including all their stats and equipment. Then give it methods to alter its state, like this:

class Player {
     private int hp;
     void modifyHP(int amount) {
          hp = hp + amount;
          // test if 0 < hp < max hp
     }
}

Then think about what your items have in common. All of them can probably be "used" in some fashion. You could create an interface called Item that includes methods that can be called on any Item. (Or if it makes sense to have code in common between Items, make Item a class.) Either way, your potion could look something like this:

class Potion implements Item {
     private boolean used = false;
     void useItem(Player target) {
          if(used == false) {
               target.modifyHP(50);
               used = true;
          }
     }
}

Then when your player drinks a potion, it might look like this:

Player self = new Player();
Item[] inventory = new Item[20];
inventory[0] = new Potion();
// yadda yadda
inventory[0].useItem(self);

[EternalFacepalm]

Ah, thanks!