Java Code Example: Detecting and Removing Inconsistent Data in AP CS A

📚 Quick Study Guide

• 🔍 Identifying Inconsistent Data: This involves recognizing data points that violate established rules, constraints, or expected formats within a dataset. It's a critical first step.
• 🛠️ Common Causes: Look for typos, incorrect data types, outdated information, or integration errors as primary sources of inconsistencies.
• 🛡️ Data Validation: Implement validation checks at the point of data entry or during processing. This can include type checking, range checks, and format validation using `if` statements and loops.
• 🧹 Data Cleaning Techniques: Apply strategies to correct or remove inconsistent data. Common methods include: replacing incorrect values with default values, removing entire records, or transforming data to fit a consistent format.
• 🔄 String Comparisons: When comparing strings (often the source of inconsistencies), be mindful of case sensitivity. Use `.equals()` for exact matches, and `.equalsIgnoreCase()` if case shouldn't matter.
• 🔢 Numerical Checks: Use appropriate comparison operators (`<`, `>`, `==`, `!=`, `<=`, `>=`) to ensure numerical data falls within acceptable ranges.
• 💡 Defensive Programming: Assume that data might be inconsistent and write code that handles these cases gracefully. Use `try-catch` blocks to handle potential exceptions.

Practice Quiz

1. Which of the following is the MOST likely cause of inconsistent data in an AP CS A program dealing with student grades?
   1. A) Using the correct data type for all variables.
   2. B) Inputting a grade of "110" when the valid range is 0-100.
   3. C) Properly initializing all variables before use.
   4. D) Thoroughly commenting the code.
2. What Java method is best suited for performing a case-insensitive comparison of two String values representing student names?
   1. A) `.equals()`
   2. B) `.compareTo()`
   3. C) `.equalsIgnoreCase()`
   4. D) `.length()`
3. Which programming construct is most effective for validating that a student's age is within a reasonable range (e.g., 14-19)?
   1. A) A `for` loop
   2. B) An `if` statement
   3. C) A `while` loop
   4. D) A `switch` statement
4. What is the primary purpose of data cleaning in the context of inconsistent data?
   1. A) To obfuscate the data for security purposes.
   2. B) To correct or remove inaccurate or invalid data.
   3. C) To increase the size of the dataset.
   4. D) To speed up program execution.
5. Suppose you are reading student records from a file, and one record has a missing GPA. What is a reasonable approach to handle this inconsistency?
   1. A) Assign a random GPA value.
   2. B) Skip the record entirely or assign a default GPA (e.g., 0.0).
   3. C) Crash the program.
   4. D) Attempt to calculate GPA from other unrelated data.
6. Which of the following is NOT a common technique for detecting inconsistent data?
   1. A) Range checks
   2. B) Type checking
   3. C) Random number generation
   4. D) Format validation
7. What is the benefit of using `try-catch` blocks when processing potentially inconsistent data?
   1. A) They automatically correct the inconsistent data.
   2. B) They allow the program to handle unexpected errors gracefully.
   3. C) They prevent the inconsistent data from being processed.
   4. D) They speed up program execution.