package swa.prakt3; public class ArithmeticAddition extends ArithmeticOperation { public ArithmeticAddition(ArithmeticExpression operand1, ArithmeticExpression operand2) { super(operand1, operand2); operationSign="+"; } @Override public Number doOperation(Number op1, Number op2) { return op1.doubleValue() + op2.doubleValue() ; } }