/*
 * Karp.java
 *
 * Created on neljapäev, 4. Oktoober 2007. a, 12:16
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package hoiukassa;
import java.io.*;
/**
 *
 * @author haldur
 */
public class Karp {
    
    private String failinimi;
    /** Creates a new instance of Karp */
    public Karp(String failinimi) {
        this.failinimi=failinimi;
    }
    public int kysiSumma() throws IOException{
       BufferedReader failist=new BufferedReader(
               new FileReader(failinimi));
       int vastus=Integer.parseInt(failist.readLine());
       failist.close();
       return vastus;
    }
    private void kirjutaSumma(int summa) throws IOException{
        FileWriter faili=new FileWriter(failinimi);
        faili.write(String.valueOf(summa));
        faili.close();
    }
    public void lisaSumma(int summa) throws IOException{
       if(summa<0){
         throw new ArithmeticException("Negatiivne summa");
       }
       kirjutaSumma(kysiSumma()+summa);
    }
    public void eemaldaSumma(int summa) throws IOException, KarbiException{
       if(kysiSumma()-summa<0){
          throw new KarbiException("Karbis pole piisavalt raha");
       }
       kirjutaSumma(kysiSumma()-summa);
    }
}