Employee

public class Employee {

    private String name;
    private Task currentTask;
    private double hoursLeft;

    public Employee(String name) {
        this.name = name;
        // or this.setName(name); ?
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        if (name.isEmpty()) {
            throw new IllegalArgumentException("Employee's name can not be empty!");
        }
        else {
            this.name = name;
        }
    }

    public Task getCurrentTask() {
        return this.currentTask;
    }

    public void setCurrentTask(Task task) {
        if (task == null) {
            throw new IllegalArgumentException("Task is not defined!");
        }
        else {
            this.currentTask = task;
        }
    }

    public double getHoursLeft() {
        return this.hoursLeft;
    }

    public void setHoursLeft(double hoursLeft) {
        if (hoursLeft <= 0) {
            throw new IllegalArgumentException("Hours left can not be negative or = 0!");
        }
        else {
            this.hoursLeft = hoursLeft;
        }
    }

    public void work() {
        if (this.currentTask == null) {
            System.out.println("Employee doesn't have a current task.");
            return;
        }
        if (this.hoursLeft <= 0) {
            System.out.println("Employee doesn't have any hours left for today.");
            return;
        }
        if (this.currentTask.getWorkingHours() <= 0) {
            System.out.println("Task is already finished.");
            return;
        }
        double taskHours = this.currentTask.getWorkingHours();
        double employeeHours = this.hoursLeft;
        if (taskHours > employeeHours) {
            taskHours -= employeeHours;
            employeeHours = 0;
        }
        else if (employeeHours > taskHours) {
            employeeHours -= taskHours;
            taskHours = 0;
        }
        else {
            employeeHours = 0;
            taskHours = 0;
        }
        this.currentTask.setWorkingHours(taskHours);
        this.hoursLeft = employeeHours;
        showReport();
    }

    public void showReport() {
        String report = "Employee name: " + this.name + ", Task name: " + this.currentTask.getName() +
                "\nEmployee hours left: " + this.hoursLeft + ", Task hours left: " +
                this.currentTask.getWorkingHours();
        System.out.println(report);
    }
}