variable.setCalculation(CalculationEnum.SYSTEM);
JRDesignExpression expression = new JRDesignExpression();
expression.setValueClass(java.lang.Integer.class);
expression.setText("($V{CityNumber} != null)?(new Integer($V{CityNumber}.intValue() + 1)):(new Integer(1))");
variable.setInitialValueExpression(expression);
jasperDesign.addVariable(variable);
variable = new JRDesignVariable();
variable.setName("AllCities");
variable.setValueClass(java.lang.String.class);
variable.setResetType(ResetTypeEnum.REPORT);