Remote repositories are copies of a repo that are hosted on remote computers. They are especially useful for sharing the revision history of a codebase among team members of a multi-person project. They can also serve as a remote backup of your code base.

You can clone a remote repo onto your computer which will create a copy of a remote repo on your computer, including the version history as the remote repo.

You can push new commits in your clone to the remote repo which will copy the new commits onto the remote repo. Note that pushing to a remote repo requires you to have write-access to it.

You can pull from the remote repos to receive new commits in the remote repo. Pulling is used to sync your local repo with latest changes to the remote repo.

While it is possible to set up your own remote repo on a server, an easier option is to use a remote repo hosting service such as GitHub or BitBucket.

A fork is a remote copy of a remote repo. If there is a remote repo that you want to push to but you do not have write access to it, you can fork the remote repo, which gives you your own remote repo that you can push to.

A pull request is mechanism for contributing code to a remote repo. It is a formal request sent to the maintainers of the repo asking them to pull your new code to their repo.

Clone the sample repo samplerepo-things to your computer.

Clone the sample repo as explained in [Textbook Tools → Git & GitHub → Clone].

Delete the last two commits to simulate cloning the repo 2 commits ago.

Right-click the target commit (i.e. the commit that is 2 commits behind the tip) and choose Reset current branch to this commit.

Choose the Hard - … option and click OK.

This is what you will see.

Note the following (cross refer the screenshot above):

Arrow marked as a: The local repo is now at this commit, marked by the master label.
Arrow marked as b: origin/master label shows what is the latest commit in the master branch in the remote repo.

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Use the reset command to delete commits at the tip of the revision history.

git reset --hard HEAD~2

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Now, your local repo state is exactly how it would be if you had cloned the repo 2 commits ago, as if somebody has added two more commits to the remote repo since you cloned it. To get those commits to your local repo (i.e. to sync your local repo with upstream repo) you can do a pull.

Click the Pull button in the main menu, choose origin and master in the next dialog, and click OK.

Now you should see something like this where master and origin/master are both pointing the same commit.

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git pull origin

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1. Create a GitHub account if you don't have one yet.

2. Fork the samplerepo-things to your GitHub account:

   Navigate to the on GitHub and click on the button on the top-right corner.

3. Clone the fork (not the original) to your computer.

4. Create some commits in your repo.

5. Push the new commits to your fork on GitHub

Click the Push button on the main menu, ensure the settings are as follows in the next dialog, and click the Push button on the dialog.

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Use the command git push origin master. Enter Github username and password when prompted.

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To push an existing local repo into a new remote repo on GitHub, first you need to create an empty remote repo on GitHub.

1. Login to your GitHub account and choose to create a new Repo.
   

2. In the next screen, provide a name for your repo but keep the Initialize this repo ... tick box unchecked.
   

3. Note the URL of the repo. It will be of the form https://github.com/{your_user_name}/{repo_name}.git
   e.g., https://github.com/johndoe/foobar.git
   

Next, you can push the existing local repo to the new remote repo as follows:

You can organize your types (i.e., classes, interfaces, enumerations, etc.) into packages for easier management (among other benefits).

To create a package, you put a package statement at the very top of every source file in that package. The package statement must be the first line in the source file and there can be no more than one package statement in each source file.

package seedu.tojava.util;

public class Formatter {
    public static final String PREFIX = ">>";

    public static String format(String s){
        return PREFIX + s;
    }
}

Package names are written in all lower case (not camelCase), using the dot as a separate. Companies use their reversed Internet domain name to begin their package names. Packages in the Java language itself begin with java. or javax.

To use a public package member from outside its package, you must do one of the following:

1. Use the fully qualified name to refer to the member
2. Import the package or the specific package member

package seedu.tojava;

import seedu.tojava.util.StringParser;
import seedu.tojava.frontend.*;

public class Main {

    public static void main(String[] args) {

        // Using the fully qualified name to access the Processor class
        String status = seedu.tojava.logic.Processor.getStatus();

        // Using the StringParser previously imported
        StringParser sp = new StringParser();

        // Using classes from the tojava.frontend package
        Ui ui = new Ui();
        Message m = new Message();

    }
}

Importing a package does not import its sub-packages, as packages do not behave as hierarchies despite appearances.

If you do not use a package statement, your type doesn't have a package -- a practice not recommended (except for small code examples) as it is not possible for a type in a package to import a type that is not in a package.

Optionally, a static import can be used to import static members of a type so that the imported members can be used without specifying the type name.

import static seedu.tojava.util.Formatter.PREFIX;
import static seedu.tojava.util.Formatter.format;

public class Main {

    public static void main(String[] args) {

        String formatted = format("Hello");
        boolean isFormatted = formatted.startsWith(PREFIX);
        System.out.println(formatted);
    }
}

package seedu.tojava.util;

public class Formatter {
    public static final String PREFIX = ">>";

    public static String format(String s){
        return PREFIX + s;
    }
}

The package of a type should match the folder path of the source file. Similarly, the compiler will put the .class files in a folder structure that matches the package names.

When using the commandline to compile/run Java, you should take the package into account.

Access level modifiers determine whether other classes can use a particular field or invoke a particular method.

There are two levels of access control:

1. At the class level:

   • public: the class is visible to all classes everywhere
   • no modifier (the default, also known as package-private): it is visible only within its own package
     
     

2. At the member level:

   • public or no modifier (package-private): same meaning as when used with top-level classes
   • private: the member can only be accessed in its own class
   • protected: the member can only be accessed within its own package (as with package-private) and, in addition, by a subclass of its class in another package

The following table shows the access to members permitted by each modifier.

Access levels affect you in two ways:

1. When you use classes that come from another source, such as the classes in the Java platform, access levels determine which members of those classes your own classes can use.
2. When you write a class, you need to decide what access level every member variable and every method in your class should have.

Javadoc is a tool for generating API documentation in HTML format from doc comments in source. In addition, modern IDEs use JavaDoc comments to generate explanatory tool tips.

/**
 * Returns an Image object that can then be painted on the screen.
 * The url argument must specify an absolute {@link URL}. The name
 * argument is a specifier that is relative to the url argument.
 * <p>
 * This method always returns immediately, whether or not the
 * image exists. When this applet attempts to draw the image on
 * the screen, the data will be loaded. The graphics primitives
 * that draw the image will incrementally paint on the screen.
 *
 * @param url an absolute URL giving the base location of the image
 * @param name the location of the image, relative to the url argument
 * @return the image at the specified URL
 * @see Image
 */
 public Image getImage(URL url, String name) {
        try {
            return getImage(new URL(url, name));
        } catch (MalformedURLException e) {
            return null;
        }
 }

In the absence of more extensive guidelines (e.g., given in a coding standard adopted by your project), you can follow the two examples below in your code.

A minimal javadoc comment example for methods:

/**
 * Returns lateral location of the specified position.
 * If the position is unset, NaN is returned.
 *
 * @param x  X coordinate of position.
 * @param y Y coordinate of position.
 * @param zone Zone of position.
 * @return Lateral location.
 * @throws IllegalArgumentException  If zone is <= 0.
 */
public double computeLocation(double x, double y, int zone)
    throws IllegalArgumentException {
  ...
}

A minimal javadoc comment example for classes:

package ...

import ...

/**
 * Represents a location in a 2D space. A <code>Point</code> object corresponds to
 * a coordinate represented by two integers e.g., <code>3,6</code>
 */
public class Point{
    //...
}

A software requirement specifies a need to be fulfilled by the software product.

A software project may be,

• a brown-field project i.e., develop a product to replace/update an existing software product
• a green-field project i.e., develop a totally new system with no precedent

In either case, requirements need to be gathered, analyzed, specified, and managed.

Requirements come from stakeholders.

Identifying requirements is often not easy. For example, stakeholders may not be aware of their precise needs, may not know how to communicate their requirements correctly, may not be willing to spend effort in identifying requirements, etc.

There are two kinds of requirements:

1. Functional requirements specify what the system should do.
2. Non-functional requirements specify the constraints under which system is developed and operated.

We may have to spend an extra effort in digging NFRs out as early as possible because,

1. NFRs are easier to miss  e.g., stakeholders tend to think of functional requirements first
2. sometimes NFRs are critical to the success of the software.  E.g. A web application that is too slow or that has low security is unlikely to succeed even if it has all the right functionality.

Requirements can be prioritized based the importance and urgency, while keeping in mind the constraints of schedule, budget, staff resources, quality goals, and other constraints.

A common approach is to group requirements into priority categories. Note that all such scales are subjective, and stakeholders define the meaning of each level in the scale for the project at hand.

Some requirements can be discarded if they are considered ‘out of scope ’.

Here are some characteristics of well-defined requirements ^{[📖 zielczynski]}:

• Unambiguous
• Testable (verifiable)
• Clear (concise, terse, simple, precise)
• Correct
• Understandable
• Feasible (realistic, possible)
• Independent
• Atomic
• Necessary
• Implementation-free (i.e. abstract)

Besides these criteria for individual requirements, the set of requirements as a whole should be

• Consistent
• Non-redundant
• Complete

In a brainstorming session there are no "bad" ideas. The aim is to generate ideas; not to validate them. Brainstorming encourages you to "think outside the box" and put "crazy" ideas on the table without fear of rejection.

Studying existing products can unearth shortcomings of existing solutions that can be addressed by a new product. Product manuals and other forms of technical documentation of an existing system can be a good way to learn about how the existing solutions work.

Observing users in their natural work environment can uncover product requirements. Usage data of an existing system can also be used to gather information about how an existing system is being used, which can help in building a better replacement  e.g. to find the situations where the user makes mistakes when using the current system.

Surveys can be used to solicit responses and opinions from a large number of stakeholders regarding a current product or a new product.

Interviewing stakeholders and domain experts can produce useful information that project requirements.

Focus groups are a kind of informal interview within an interactive group setting. A group of people (e.g. potential users, beta testers) are asked about their understanding of a specific issue, process, product, advertisement, etc.

Prototyping can uncover requirements, in particular, those related to how users interact with the system. UI prototypes are often used in brainstorming sessions, or in meetings with the users to get quick feedback from them.

^{[source: http://balsamiq.com/products/mockups]}

💡 Prototyping can be used for discovering as well as specifying requirements  e.g. a UI prototype can serve as a specification of what to build.

A textual description (i.e. prose) can be used to describe requirements. Prose is especially useful when describing abstract ideas such as the vision of a product.

Avoid using lengthy prose to describe requirements; they can be hard to follow.

A common format for writing user stories is:

We can write user stories on index cards or sticky notes, and arrange on walls or tables, to facilitate planning and discussion. Alternatively, we can use a software (e.g., GitHub Project Boards, Trello, Google Docs, ...) to manage user stories digitally.

^{[credit: https://www.flickr.com/photos/jakuza/2682466984/]}

^{[credit: https://www.flickr.com/photos/jakuza/with/2726048607/]}

^{[credit: https://commons.wikimedia.org/wiki/File:User_Story_Map_in_Action.png]}

The {benefit} can be omitted if it is obvious.

💡 It is recommended to confirm there is a concrete benefit even if you omit it from the user story. If not, you could end up adding features that have no real benefit.

You can add more characteristics to the {user role} to provide more context to the user story.

You can write user stories at various levels. High-level user stories, called epics (or themes) cover bigger functionality. You can then break down these epics to multiple user stories of normal size.

You can add conditions of satisfaction to a user story to specify things that need to be true for the user story implementation to be accepted as ‘done’.

Other useful info that can be added to a user story includes (but not limited to)

• Priority: how important the user story is
• Size: the estimated effort to implement the user story
• Urgency: how soon the feature is needed

User stories capture user requirements in a way that is convenient for scoping, estimation and scheduling.

[User stories] strongly shift the focus from writing about features to discussing them. In fact, these discussions are more important than whatever text is written. _{[Mike Cohn, MountainGoat Software 🔗]}

User stories differ from traditional requirements specifications mainly in the level of detail. User stories should only provide enough details to make a reasonably low risk estimate of how long the user story will take to implement. When the time comes to implement the user story, the developers will meet with the customer face-to-face to work out a more detailed description of the requirements. [more...]

User stories can capture non-functional requirements too because even NFRs must benefit some stakeholder.

While use cases can be recorded on physical paper in the initial stages, an online tool is more suitable for longer-term management of user stories, especially if the team is not co-located.

A use case describes an interaction between the user and the system for a specific functionality of the system.

UML includes a diagram type called use case diagrams that can illustrate use cases of a system visually , providing a visual ‘table of contents’ of the use cases of a system. In the example below, note how use cases are shown as ovals and user roles relevant to each use case are shown as stick figures connected to the corresponding ovals.

Use cases capture the functional requirements of a system.

A supplementary requirements section can be used to capture requirements that do not fit elsewhere. Typically, this is where most Non Functional Requirements will be listed.