2Do - Developer Guide

1. Setting up

1.1. Prerequisites

JDK 1.8.0_60 or later

Having any Java 8 version is not enough.
This app will not work with earlier versions of Java 8.
Eclipse IDE
e(fx)clipse plugin for Eclipse (Do the steps 2 onwards given in this page)
Buildship Gradle Integration plugin from the Eclipse Marketplace
Checkstyle Plug-in plugin from the Eclipse Marketplace

1.2. Importing the project into Eclipse

Fork this repo, and clone the fork to your computer
Open Eclipse (Note: Ensure you have installed the e(fx)clipse and buildship plugins as given in the prerequisites above)
Click File > Import
Click Gradle > Gradle Project > Next > Next
Click Browse, then locate the project’s directory
Click Finish

If you are asked whether to 'keep' or 'overwrite' config files, choose to 'keep'.
Depending on your connection speed and server load, it can even take up to 30 minutes for the set up to finish (This is because Gradle downloads library files from servers during the project set up process).
If Eclipse auto-changed any settings files during the import process, you can discard those changes.

1.3. Configuring checkstyle

Click Project → Properties → Checkstyle → Local Check Configurations → New…
Choose External Configuration File under Type
Enter an arbitrary configuration name e.g. 2Do
Import checkstyle configuration file found at config/checkstyle/checkstyle.xml
Click OK once, go to the Main tab, use the newly imported check configuration.
Tick and select files from packages, click Change…, and select the resources package
Click OK twice. Rebuild project if prompted

Click on the files from packages text after ticking in order to enable the Change… button

1.4. Troubleshooting project setup

Problem: Eclipse reports compile errors after new commits are pulled from Git

Reason: Eclipse fails to recognize new files that appeared due to the Git pull.
Solution: Refresh the project in Eclipse: Right click on the project (in Eclipse package explorer), choose Gradle → Refresh Gradle Project.

Problem: Eclipse reports some required libraries missing

Reason: Required libraries may not have been downloaded during the project import.
Solution: Run tests using Gradle once (to refresh the libraries).

1.5. Updating documentation

After forking the repo, links in the documentation will link to the wrong repo. You should replace the URL in the variable repoURL in DeveloperGuide.adoc with the URL of your fork.

2. Design

2.1. Architecture

Figure 2.1.1 : Architecture Diagram

The Architecture Diagram given above explains the high-level design of 2Do. Given below is a quick overview of each component.

The .pptx files used to create diagrams in this document can be found in the diagrams folder. To update a diagram, modify the diagram in the pptx file, select the objects of the diagram, and choose Save as picture.

Main has only one class called MainApp. It is responsible for,

At app launch: Initializes the components in the correct sequence, and connects them up with each other.
At shut down: Shuts down the components and invokes cleanup method where necessary.

Commons represents a collection of classes used by multiple other components. Two of those classes play important roles at the architecture level.

EventsCenter : This class (written using Google’s Event Bus library) is used by components to communicate with other components using events (i.e. a form of Event Driven design)
LogsCenter : Used by many classes to write log messages to 2Do's log file.

The rest of the App consists of four components.

UI : The user interface of 2Do.
Logic : The command executor.
Model : Holds the data of 2Do in-memory.
Storage : Reads data from, and writes data to, the hard disk.

Each of the four components

Defines its API in an interface with the same name as the Component.
Exposes its functionality using a {Component Name}Manager class.

For example, the Logic component (see the simplified class diagram given below) defines it’s API in the Logic.java interface and exposes its functionality using the LogicManager.java class.

Figure 2.1.2 : Simplified class Diagram of the Logic Component

Events-Driven nature of the design

The Sequence Diagram below shows how the components interact for the scenario where the user issues the command delete 1.

Figure 2.1.3a : Component interactions for delete 1 command (part 1)

Note how the Model simply raises a TaskBookChangedEvent when the TaskList data are changed, instead of asking the Storage to save the updates to the hard disk.

The diagram below shows how the EventsCenter reacts to that event, which eventually results in the updates being saved to the hard disk and the status bar of the UI being updated to reflect the 'Last Updated' time.

Figure 2.1.3b : Component interactions for delete 1 command (part 2)

Note how the event is propagated through the EventsCenter to the Storage and UI without Model having to be coupled to either of them. This is an example of how this Event Driven approach helps us reduce direct coupling between components.

The sections below give more details of each component.

2.2. UI component

Author: Yogamurti Sutanto

Figure 2.2.1 : Structure of the UI Component

API : Ui.java

The UI consists of a MainWindow that is made up of parts e.g.CommandBox, ResultDisplay, CategoryListPanel, etc. All these, including the MainWindow, inherit from the abstract UiPart class.

The UI component uses the JavaFx UI framework. The layout of these UI parts are defined in matching .fxml files that are in the src/main/resources/view folder. For example, the layout of the MainWindow is specified in MainWindow.fxml

Model-View-Controller Pattern
2Do decouples its data, presentation, and control logic by separating them into three different components: Model, View and Controller.

Model: The UI component’s ResultDisplay, CategoryListPanel, TaskListPanel, StatusBarFooter and HelpWindow binds themselves to some data in the Model component, which stores and maintains data in 2Do.
View: The UI component is responsible for displaying data, interacting with the user through the Logic component, and getting automatic data updates from the Model component.
Controller: The UI component’s CommandBox is responsible for detecting user command inputs and forwarding them to the Logic component, which executes the commands.

Observer Pattern
2Do utilizes the observer pattern to avoid direct coupling between the UI component and other components.

The UI component’s constituents that depends on data from the Model component, such as its TaskListPanel constituent, requires notification whenever the Model component updates.

This is done by the TaskListChangedEvent.

Whenever the data in the Model component updates, 2Do notifies its relevant UI constituents by calling a indicateTaskListChanged() operation, which raises a new TaskListChangedEvent. This event will call the relevant UI constituents to update their data from the Model component and display the updated data.

2.3. Logic component

Author: Ang Lang Yi

Figure 2.3.1 : Structure of the Logic Component

API : Logic.java

Logic uses the Parser class to parse the user command.
The command parsing of each specific command is encapsulated as a CommandParser object for the their respective parser objects (e.g. DeleteCommandParser).
This results in a Command object which is executed by the LogicManager. <<<<<<< HEAD <<<<<<< HEAD
The command execution can affect the Model (e.g. deleting a task) and/or raise events.
The result of the command execution is encapsulated as a CommandResult object which is passed back to the Ui.

The command execution can affect the Model (e.g. adding a task) and/or raise events.
The result of the command execution is encapsulated as a CommandResult object which is passed back to the UI. >>>>>>> e2316be8bb13260459565087a7d96bb8606b2dc9

The command execution can affect the Model (e.g. deleting a task) and/or raise events.
The result of the command execution is encapsulated as a CommandResult object which is passed back to the UI. >>>>>>> 3c0b763810c18937d0cf92df331c1ae1e2ed24bd

Given below is the Sequence Diagram for interactions within the Logic component for the execute("delete 1") API call.

Figure 2.3.1 : Interactions Inside the Logic Component for the delete 1 Command

2.4. Model component

Author: V Narendar Nag

Figure 2.4.1 : Structure of the Model Component

API : Model.java

The Model,

stores a UserPref object that represents the user’s preferences.
stores the Taskbook data.
exposes a UnmodifiableObservableList<ReadOnlyTask> that can be 'observed' e.g. the UI can be bound to this list so that the UI automatically updates when the data in the list change.
does not depend on any of the other three components.

2.5. Storage component

Author: Teo Shu Qi

Figure 2.5.1 : Structure of the Storage Component

API : Storage.java

The Storage component,

can save UserPref objects in json format and read it back.
can save the TaskList data in xml format and read it back.

2Do allows users to save their data at a new filepath(File Directory must be available). The filepath can be specified via the Save command and will contain a new 2Do.xml document. StorageMananger will set the new filepath and save it into Config. 2Do will load from and save to the new filepath for current and future sessions until a new filepath is specified. 2Do also allows users to load a TaskList file from previous sessions vias the Load command.

2.6. Common classes

Classes used by multiple components are in the teamthree.twodo.commons package.

3. Implementation

3.1. Logging

We are using java.util.logging package for logging. The LogsCenter class is used to manage the logging levels and logging destinations.

The logging level can be controlled using the logLevel setting in the configuration file (See Configuration)
The Logger for a class can be obtained using LogsCenter.getLogger(Class) which will log messages according to the specified logging level
Currently log messages are output through: Console and to a .log file.

Logging Levels

SEVERE : Critical problem detected which may possibly cause the termination of the application
WARNING : Can continue, but with caution
INFO : Information showing the noteworthy actions by the App
FINE : Details that is not usually noteworthy but may be useful in debugging e.g. print the actual list instead of just its size

3.2. Configuration

Certain properties of the application can be controlled (e.g App name, logging level) through the configuration file (default: config.json).

4. Testing

Tests can be found in the ./src/test/java folder.

In Eclipse:

To run all tests, right-click on the src/test/java folder and choose Run as > JUnit Test
To run a subset of tests, you can right-click on a test package, test class, or a test and choose to run as a JUnit test.

Using Gradle:

See UsingGradle.adoc for how to run tests using Gradle.

We have two types of tests:

GUI Tests - These are System Tests that test the entire App by simulating user actions on the GUI. These are in the guitests package.
Non-GUI Tests - These are tests not involving the GUI. They include,
1. Unit tests targeting the lowest level methods/classes.
  e.g. teamthree.twodo.commons.StringUtilTest
2. Integration tests that are checking the integration of multiple code units (those code units are assumed to be working).
  e.g. teamthree.twodo.storage.StorageManagerTest
3. Hybrids of unit and integration tests. These test are checking multiple code units as well as how the are connected together.
  e.g. teamthree.twodo.logic.LogicManagerTest

4.1. Headless GUI Testing

Thanks to the TestFX library we use, our GUI tests can be run in the headless mode. In the headless mode, GUI tests do not show up on the screen. That means the developer can do other things on the Computer while the tests are running. See UsingGradle.adoc to learn how to run tests in headless mode.

4.2. Troubleshooting tests

Problem: Tests fail because NullPointException when AssertionError is expected

Reason: Assertions are not enabled for JUnit tests. This can happen if you are not using a recent Eclipse version (i.e. Neon or later)
Solution: Enable assertions in JUnit tests as described here. Delete run configurations created when you ran tests earlier.

5. Dev Ops

5.1. Build Automation

See UsingGradle.adoc to learn how to use Gradle for build automation.

5.2. Continuous Integration

We use Travis CI and AppVeyor to perform Continuous Integration on our projects. See UsingTravis.adoc and UsingAppVeyor.adoc for more details.

5.3. Publishing Documentation

See UsingGithubPages.adoc to learn how to use GitHub Pages to publish documentation to the project site.

5.4. Making a Release

Here are the steps to create a new release.

Generate a JAR file using Gradle.
Tag the repo with the version number. e.g. v0.1
Create a new release using GitHub and upload the JAR file you created.

5.5. Converting Documentation to PDF format

We use Google Chrome for converting documentation to PDF format, as Chrome’s PDF engine preserves hyperlinks used in webpages.

Here are the steps to convert the project documentation files to PDF format.

Make sure you have set up GitHub Pages as described in UsingGithubPages.adoc.
Using Chrome, go to the GitHub Pages version of the documentation file. e.g. For UserGuide.adoc, the URL will be https://<your-username-or-organization-name>.github.io/main/docs/UserGuide.html.
Click on the Print option in Chrome’s menu.
Set the destination to Save as PDF, then click Save to save a copy of the file in PDF format. For best results, use the settings indicated in the screenshot below.

Figure 5.4.1 : Saving documentation as PDF files in Chrome

5.6. Managing Dependencies

A project often depends on third-party libraries. For example, 2Do depends on the Jackson library for XML parsing and the PrettyTime library for natural language handling. Managing these dependencies can be automated using Gradle. Gradle can download the dependencies automatically, which is better than these alternatives:
a. Including those libraries in the repository (this bloats the repository size)
b. Require developers to download those libraries manually (this creates extra work for developers)

Appendix A: User Stories

Priorities: High (must have) - * * *, Medium (nice to have) - * *, Low (unlikely to have) - *

Priority As a … I want to … So that I can…

Priority	As a …	I want to …	So that I can…
`* * *`	new user	see usage instructions	refer to instructions when I forget how to use 2Do
`* * *`	user	add floating tasks	manage my floating tasks
`* * *`	user	add tasks with deadlines	manage my tasks with deadlines
`* * *`	user	add events	manage my events
`* * *`	user	describe my tasks in detail	add more information about the tasks, such as the venue
`* * *`	user	delete tasks	remove tasks that have been cancelled
`* * *`	user	edit tasks	update my task details for unforeseen circumstances, such as postponing a deadline
`* * *`	user	add deadlines to my floating tasks	update my floating tasks if they then require a deadline
`* * *`	user	mark my tasks as completed	stop being reminded for tasks I have done
`* * *`	user	mark completed tasks as uncompleted again	appropriately update my to-do list if the task then requires more follow-up action
`* * *`	user	list all my uncompleted tasks	know what I need to do
`* * *`	user	list all my completed tasks	review and reflect on the tasks I have done
`* * *`	user	search for tasks using keywords	find details of specific tasks
`* * *`	user	find tasks that are related by some category	know related tasks easily if I have tagged them with their respective categories
`* * *`	user	find tasks by deadline	know which tasks are most urgent
`* * *`	user	save my to-do list as a readable file	have a back-up copy of my to-do list and be able to view it across multiple devices
`* * *`	user	undo the last action	correct a mistake
`* * *`	user	have flexible command formats	execute actions in a more natural manner
`* *`	user	add recurring tasks	not need to add the same task every time it repeats
`* *`	user	mark tasks as cannot do	properly remove tasks that I am unable to complete out of my to-do list
`* *`	user	list tasks this week or month	see only tasks with urgent deadlines to prevent clutter
`* *`	user	set a reminder on tasks	be reminded of my tasks closer to their deadline
`* *`	user	have a global reminder setting	not need to set reminders for each task manually
`* *`	user	be alerted of tasks whose deadline has eclipsed but I have not marked as complete	decide on an appropriate follow-up action
`* *`	user	load a to-do list from a storage location	manage my to-do list from different devices and be able to manage multiple to-do lists
`* *`	user	redo a command I have undone	redo any unintended undo actions
`* *`	user	have command shortcuts	execute actions with ease and speed
`* *`	user with many tagged tasks	clear all tasks that have a certain tag	conveniently clear all related tasks once a project or milestone is completed or cancelled
`*`	user	visualize my tasks as a calendar	more easily plan my schedule
`*`	user	launch the program quickly, by pressing a keyboard shortcut	conveniently launch the program
`*`	experienced user	create my own shortcuts for my most frequently used commands	more conveniently use the program
`*`	user with many tasks	sort tasks in different ways	gain a better understanding of the tasks at hand
`*`	user	get directions	get directions to the task’s location, from my current location
`*`	user	block timeslots for events	stop scheduling events with conflicting timings
`*`	user	unblock timeslots that have been blocked	schedule other events in that timeslot
`*`	user	synchronize my tasks with my google calendar	access my to-do list from public computers

* * *

new user

see usage instructions

refer to instructions when I forget how to use 2Do

* * *

user

add floating tasks

manage my floating tasks

* * *

user

add tasks with deadlines

manage my tasks with deadlines

* * *

user

add events

manage my events

* * *

user

describe my tasks in detail

add more information about the tasks, such as the venue

* * *

user

delete tasks

remove tasks that have been cancelled

* * *

user

edit tasks

update my task details for unforeseen circumstances, such as postponing a deadline

* * *

user

add deadlines to my floating tasks

update my floating tasks if they then require a deadline

* * *

user

mark my tasks as completed

stop being reminded for tasks I have done

* * *

user

mark completed tasks as uncompleted again

appropriately update my to-do list if the task then requires more follow-up action

* * *

user

list all my uncompleted tasks

know what I need to do

* * *

user

list all my completed tasks

review and reflect on the tasks I have done

* * *

user

search for tasks using keywords

find details of specific tasks

* * *

user

find tasks that are related by some category

know related tasks easily if I have tagged them with their respective categories

* * *

user

find tasks by deadline

know which tasks are most urgent

* * *

user

save my to-do list as a readable file

have a back-up copy of my to-do list and be able to view it across multiple devices

* * *

user

undo the last action

correct a mistake

* * *

user

have flexible command formats

execute actions in a more natural manner

* *

user

add recurring tasks

not need to add the same task every time it repeats

* *

user

mark tasks as cannot do

properly remove tasks that I am unable to complete out of my to-do list

* *

user

list tasks this week or month

see only tasks with urgent deadlines to prevent clutter

* *

user

set a reminder on tasks

be reminded of my tasks closer to their deadline

* *

user

have a global reminder setting

not need to set reminders for each task manually

* *

user

be alerted of tasks whose deadline has eclipsed but I have not marked as complete

decide on an appropriate follow-up action

* *

user

load a to-do list from a storage location

manage my to-do list from different devices and be able to manage multiple to-do lists

* *

user

redo a command I have undone

redo any unintended undo actions

* *

user

have command shortcuts

execute actions with ease and speed

* *

user with many tagged tasks

clear all tasks that have a certain tag

conveniently clear all related tasks once a project or milestone is completed or cancelled

*

user

visualize my tasks as a calendar

more easily plan my schedule

*

user

launch the program quickly, by pressing a keyboard shortcut

conveniently launch the program

*

experienced user

create my own shortcuts for my most frequently used commands

more conveniently use the program

*

user with many tasks

sort tasks in different ways

gain a better understanding of the tasks at hand

*

user

get directions

get directions to the task’s location, from my current location

*

user

block timeslots for events

stop scheduling events with conflicting timings

*

user

unblock timeslots that have been blocked

schedule other events in that timeslot

*

user

synchronize my tasks with my google calendar

access my to-do list from public computers

Appendix B: Use Cases

For all use cases below, the System is 2Do and the Actor is the user, unless specified otherwise.

Use case: Display help guide

MSS

User requests for the help guide
System displays the help guide

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Add a floating task

MSS

User requests to add a floating task with the name field filled and the end field empty
System adds the floating task and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

1b. User enters an alarm parameter using the natural language format

1b1. System displays an error message

Use case ends

Use case: Add a task with a deadline

MSS

User requests to add a task, with a deadline, with the name and end fields filled and the start field empty
System adds the task, with a deadline, and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Add an event

MSS

User requests to add an event with the name, start and end fields filled
System adds the event and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

1b. User enters an end time that is earlier than the start time

1b1. System displays an error message

Use case ends

Use case: Add a tag

MSS

User requests to add a tag
System adds the tag and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Delete task

MSS

User searches for a task using list or find
System displays all relevant tasks
User requests to delete the task by using its index
System deletes the task and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

3a. User input is invalid

3a1. System displays an error message

Use case resumes at step 2

Use case: Delete a tag

MSS

User requests to delete a tag
System deletes the tag and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: List tasks

MSS

User requests to list all tasks
System displays all tasks

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Find task

MSS

User requests to find a task using a keyword
System displays all relevant tasks

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Undo last action

MSS

User requests to undo the last action
System undoes the last action and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

2a. No actions were done previously

2a1. System displays an error message

Use case ends

Use case: Redo last undo command

MSS

User requests to redo the last undo command
System redoes the last undo command and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

2a. The last action was not an undo command

2a1. System displays an error message

Use case ends

Use case: Edit task

MSS

User searches for a task using list or find
System displays all relevant tasks
User requests to edit the task by using its index
System updates the task and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

3a. User input is invalid

3a1. System displays an error message

Use case resumes at step 2

Use case: Mark task as complete

MSS

User searches for a task using list or find
System displays all relevant tasks
User requests to mark the task as complete by index
System updates the task and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

3a. User input is invalid

3a1. System displays an error message

Use case resumes at step 2

3b. Task is already marked as complete

3b1. System displays an error message

Use case ends

Use case: Mark task as incomplete

MSS

User searches for a completed task using list /h or find /h
System displays all relevant tasks
User requests to mark the task as incomplete by index
System updates the task and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

3a. User input is invalid

3a1. System displays an error message

Use case resumes at step 2

3b. Task is already marked as incomplete

3b1. System displays an error message

Use case ends

Use case: Display options

MSS

User requests to view the general options available on system
System displays its general options
User requests to change the general options for the session
System updates its general options for the session and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

3a. User input is invalid

3a1. System displays an error message

Use case ends

3b. Options inputted are the same as the current general options

3b1. System displays an error message

Use case ends

Use case: Save to-do list

MSS

User requests to save the to-do list
System saves the current to-do list, exports it as an xml file in the directory specified and displays a success message

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Load to-do list

MSS

User requests to load a to-do list xml file into the system
System loads the to-do list and displays the loaded to-do list

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Clear to-do list

MSS

User requests to clear the to-do list
System clears the to-do list

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Use case: Quit system

MSS

User requests to quit system
System shuts down

Use case ends

Extensions

1a. User input is invalid

1a1. System displays an error message

Use case ends

Appendix C: Non Functional Requirements

Should work on any mainstream OS as long as it has Java 1.8.0_60 or higher installed
Should handle at least 100 tasks without a noticeable decline in performance
A user with above average typing speed for regular English text (i.e. not code, not system admin commands) should be able to accomplish most tasks faster using commands than using the mouse
Should have automated unit tests and open source code
Should have user-friendly commands
Should not require more than 3 seconds to startup
Should not require more than 2 seconds to respond to a user request
Should not require internet connection

Appendix D: Glossary

Name

Name of task

Floating task

Task without an end time

Task with deadline

Task with an end time and without a start time

Event

Task with a start time and an end time

Recurring task

Task that repeatedly needs to be done every week, month or year

Index

Number assigned to a task to ease the operation of commands (E.g. add, delete, edit)

Last action

Last command executed

History

Completed tasks

Mainstream OS

Windows, Linux, Unix, OS-X

Appendix E: Product Survey

Google Calendar

Author: Ang Lang Yi

Pros:

User friendly commands, through simply filling its short and simple forms to handle tasks
Simple interface makes it easy to navigate around
Calendar interface allows the user to easily find empty slots to schedule tasks
Calendar can be viewed in a year, month, day or agenda format
Import and view other people’s calendars for better collaboration
Reminders can be set to a task

Cons:

Floating tasks are difficult to schedule
Navigation requires mouse usage instead of command line
Internet connection is required

Todoist

Author: Teo Shu Qi

Pros:

Features are intuitive as users simply need to fill in the short and simple forms provided to handle their tasks
Different categories are available to separate different kinds of tasks
Each category allows a daily and weekly view of its tasks
Recurring tasks can be added
Different priority levels can be set for tasks
Filter and find tasks according to priority level and floating tasks

Cons:

Only tasks due for the next 7 days can be seen
Some features (e.g. comments) require a monthly subscription
Navigation requires mouse usage instead of command line
Internet connection is required

Trello

Author: V Narendar Nag

Pros:

Multiple boards can be added to segregate different categories of tasks
Lists can be added to a board to separate that category into even more sections
A team can collaborate on a board together
Reminders can be set to a task
Comments can be added to a task for additional notes
Images and attachments can be added to a task

Cons:

Adding a task is not intuitive as its respective form is cluttered with additional features that makes it difficult to know which fields are mandatory
Setting up the calendar is dependent on another calendar application (e.g. Google Calendar) as it supports calendar import by other applications but lacks its own native calendar
Recurring tasks cannot be added
A command line interface is not available
Internet connection is required

Wunderlist

Author: Yogamurti Sutanto

Pros:

Short and simple forms are used to allow easy handling of tasks
Straightforward and uncluttered interface makes it easy for navigation
Various backgrounds are available to suit the user’s preferences
Sort uncompleted tasks in various ways
Tasks can be starred to indicate importance and segregate them from other tasks
Categories can be added to tasks for better organization
Multiple users can collaborate together on a particular category of the to-do list
Reminders can be set to a task
Subtask and notes can be added to a task

Cons:

A command line interface is not available
Internet connection is required