Develop a Java application that determines whether any of several department- store customers has exceeded the credit limit on a charge account. For each customer, the following facts are available: a) account number b) balance at the beginning of the month c) total of all items charged by the customer this month d) total of all credits applied to the customer's account this month e) allowed credit limit.

Java is a powerful object-oriented programming language used for building a multitude of applications, from mobile apps to large enterprise systems. Central to Java's philosophy is the 'write once, run anywhere' (WORA) capability, which means compiled Java code can run on all platforms that support Java without the need for recompilation. In the context of our exercise, Java allows us to create a dynamic application, the 'Credit Limit Checker', which is robust and portable.

A Java application typically begins with a main method, which is the entry point of the application. This is where objects are created from classes – blueprints that define the nature and behavior of an object. In the provided exercise, the 'CreditLimitChecker' class would invoke the main method to initiate the credit limit checking process for the department store customers, leading to a seamless and efficient end-user experience.

The credit limit calculation is a critical financial assessment that helps prevent customers from overspending beyond their allotted credit cap. In our Java application, it is implemented by a simple formula:
\[\begin{equation} \text{New Balance} = \text{Initial Balance} + \text{Total Charges} - \text{Total Credits} \end{equation}\]
If the new balance is greater than the allowed credit limit, it indicates that the customer has surpassed their spending threshold. This basic calculation plays a vital role in managing financial risk for both the customers and the department store. Ensuring that the calculation is correctly implemented in code helps prevent errors that could lead to overspending or customer dissatisfaction.

In Java, a class is essentially a template for creating objects. It encapsulates data for the object and methods to manipulate that data. For the 'Credit Limit Checker' application, a 'Customer' class is designed to house various pieces of information specific to each customer, such as account number, balance, total charges, total credits, and the credit limit.

Once the 'Customer' class is defined, objects can be created from this class, with each object representing a distinct customer with individual attributes. Methods within the 'Customer' class could include actions like calculating the new balance and checking if this exceeds the pre-defined credit limit—an essential part of the application's functionality.

Retrieving user input is crucial for interactive applications. In Java, one of the standard ways to obtain input from a user is through the 'Scanner' class, which is part of the 'java.util' package. The 'Scanner' allows us to read various types of data, such as 'ints', 'doubles', and 'Strings', which are essential data types for our 'Credit Limit Checker'.

In our exercise, the Scanner reads customer details entered by the user, such as their starting balance, charges, credits, and credit limit, using relevant prompts in the console. The use of the 'Scanner' in the main method allows the program to be dynamic and user-responsive, essential for real-time credit limit checking and further exhibits the flexibility of Java for handling various forms of user input.