DynamicHelper.java

package node;


public class DynamicHelper {
    private MathProcessing[] handlers;

    public DynamicHelper(MathProcessing[] handlers) {
        this.handlers = handlers;
    }

    public String process(String statement){
        String[] parts = statement.split(MathProcessing.SEPARATER);
        String keyword = parts[0]; // add value

        MathProcessing theHandler = null;
        for (MathProcessing handler: handlers){
            if (keyword.equalsIgnoreCase(handler.getKeyword())){
                theHandler = handler;
                break;
            }
        }

        double leftVal = Double.parseDouble(parts[1]);
        double rightVal = Double.parseDouble(parts[2]);

        double result = theHandler.doCalculation(leftVal, rightVal);

        StringBuilder sb = new StringBuilder(20);
        sb.append(leftVal);
        sb.append(' ');
        sb.append(theHandler.getSymbol());
        sb.append(' ');
        sb.append(rightVal);
        sb.append(" = ");
        sb.append(result);

        return sb.toString();
    }
}