package esimene;
import java.util.Stack;
public class RpnCalculator {
    Stack<Integer> st=new Stack<Integer>();
    public void setAccumulator(int i) {
      if(st.size()>0){st.pop();}
      st.push(i);
    }

    public void plus() {
        st.push(popFromStack()+ popFromStack());
      //  enter();
    }

    public void enter() {
    	st.push(getAccumulator());        
    }

    public int getAccumulator() {
        if(st.size()>0){return st.peek();}
    	return 0;
    }
    private int popFromStack(){
    	if(st.size()>0){return st.pop();}
    	return 0;
    }
    
    public void multiply() {
    	st.push(popFromStack() * popFromStack());
    	//enter();
    }
    
    public void calculate(String data) {
        for (String element : data.split("\\s")) {
        	if ("+".equals(element)) {
        		plus();
        		enter();
        	} else if ("*".equals(element)) {
        		multiply();
        		enter();
        	} else {
        		setAccumulator(Integer.parseInt(element));
        		enter();
        	}
        }
    }
}
/*
public class RpnCalculator {
    Stack<Integer> st=new Stack<Integer>();
    int acc;
    public void setAccumulator(int i) {
      acc=i;
    }

    public void plus() {
        setAccumulator(st.pop()+ getAccumulator());
    }

    public void enter() {
        st.push(acc);
    }

    public int getAccumulator() {
        return acc;
    }
}
*/