package programming101.calculator;

import java.awt.event.ActionEvent;


/**
	* Does calculator addition and subtraction.  Handles windowing system
	* button click events directly.
	*
	* @author © 1998 Peter T. Sander
	* @version 1.0 (15/03/98)
	* @since 15/03/98
	*/
	
public class PlusButton extends CalculatorButton  {
	
	/**
		* Constructor.
		*
		* @param calculator reference to calculator using this button
		*/
	public PlusButton(Calculator calculator) {
		super("+", calculator);
	}
	
	/**
		* Handles windowing system button click events.  Basically adds
		* value in the entry field to current accumulator value.
		*
		* @param ae action event fired by the windowing system
		*/
	public final void actionPerformed(ActionEvent ae) {
		getCalculatorData();
		double entry = Double.valueOf(entryField).doubleValue();
		if (lastButton == null) {
			cumulator = entry;
		} else {
			cumulator += entry;
		}
		entryField = new Double(cumulator).toString();
		lastButton = this;
		setCalculatorData(cumulator, entryField, lastButton);
		System.out.println("PlusButton putsched: " + cumulator);
	}
}