TotalAction.java

package org.softlang.company.features.action;

import org.softlang.company.model.Department;
import org.softlang.company.model.Employee;
import org.softlang.company.features.context.Context;

/**
 * Total a department in a context
 */

public class TotalAction implements Action<Department, Double> {

    private double total = 0;

    public void execute(Context context, Department department) {
        // Delegate execution for all departments to the context
        for (Department sub : department.getSubdepts()) {
            context.execute(this, sub);
        }

        // Total manager and employees, sequentially
        addToTotal(department.getManager().getSalary());
        for (Employee e : department.getEmployees()) {
            addToTotal(e.getSalary());
        }
    }

    // Synchronized access to the aggregation variable
    private synchronized void addToTotal(double x) {
        total += x;
    }    

    /**
     * Return aggregated total assuming all threads were completed
     */
    public Double getResult() {
        return total;
    }

}