Question

Class PhoneBookClient should provide a user interface that allows the user to scroll through entries, add a new entry, modify an existing entry and delete an existing entry. The client and the server should provide proper error handling (e.g., the client cannot modify an entry that does not exist).

Short answer

Implement methods for scrolling, adding, modifying, and deleting entries with error handling.

Step-by-step solution

Identify Requirements

To solve this exercise, recognize the requirements for the PhoneBookClient class: it must allow scrolling through entries, adding new entries, modifying existing entries, and deleting existing entries. Additionally, the client must handle errors, such as attempting to modify a non-existent entry.

Implement Scrolling Functionality

Develop a method that allows users to scroll through the phone book entries. This may be a simple function that iterates over a list of entries and displays them to the user.

Implement Add Entry Function

Create a function to add a new entry to the phone book. This function should take input data such as name and phone number, and append it to the list of entries, ensuring that validations like checking for blank entries are in place.

Implement Modify Entry Function

Create a function to modify an existing entry. This requires finding the entry by a unique key (like a name or ID), allowing the user to change details, and saving the modified entry in place of the old one. Implement error handling if the entry does not exist.

Implement Delete Entry Function

Develop a function to delete an existing entry. This involves searching for the entry to ensure it exists, then removing it from the list. Proper error handling should be implemented to provide feedback if the entry is not found.

Implement Error Handling

Incorporate error handling for the client-side operations. This includes checks for attempting to modify or delete non-existent entries, ensuring that user inputs are valid, and catching any runtime errors that could occur during operations.

Test Client and Server Interaction

Test the client-side user interface by simulating interactions with a fake server or server responses. Ensure all operations are responsive and error messages are handled gracefully.

Key concepts

User Interface Design

Creating an intuitive and user-friendly interface is crucial for the PhoneBookClient class. The interface should accommodate easy navigation through the primary functions: scrolling, adding, modifying, and deleting entries. Aim for a clean and structured layout, where buttons and menus are clearly labeled for user convenience. Use visual feedback, like highlighting selected entries or confirming successful operations with a notification.
Break down the interface into distinct sections, each dedicated to a specific functionality. For scrolling, a list view with forward and backward buttons can help users navigate.
Similarly, the add and modify functions can benefit from input fields with labels that guide users on what information to provide, such as a name or phone number.

Error Handling

Error handling ensures that your application runs smoothly even when unexpected events occur. In the context of the PhoneBookClient, it's vital to prevent users from making erroneous modifications, like attempting to update or delete an entry that doesn't exist.
Implement input validation to catch potential errors early. For instance, check if a user tries to add an entry without providing a name or phone number.
Moreover, display clear error messages that explain what went wrong and how to fix it, such as 'Entry not found' or 'Name cannot be blank'. This will aid users in correcting mistakes without feeling frustrated.

Data Manipulation

Manipulating data effectively is at the heart of the PhoneBookClient functionality. Data manipulation involves several key operations: adding new entries, modifying existing entries, and deleting entries.
When adding an entry, ensure that you gather necessary information from the user and enhance the data's integrity with validation checks.
For modifying entries, locate the required entry using a unique identifier, and present the user with editable fields.
Upon completion of modifications, save the new data efficiently without disrupting the existing structure. Deletion requires checking that the targeted entry indeed exists before removing it, ensuring consistency within the dataset.

Software Testing

Testing your software is a crucial step in the development process. It's essential to verify that all features in the PhoneBookClient work as intended, both on their own and in interaction with a server.
Begin with unit tests for each function, such as adding or deleting entries, ensuring they perform correctly in isolation.
Next, carry out integration testing to confirm that the client-server communication is seamless, and error messages are correctly triggered and displayed.
Testing under various scenarios, including edge cases like empty lists, will help maintain robustness and user trust in your application. Be sure to simulate real-world usage to detect any potential issues that might only appear during typical user interactions.