Java Exceptions: Checked vs. Unchecked
In the realm of Java programming, exceptions are events that disrupt the normal flow of program execution. Two primary types of exceptions exist in Java: checked and unchecked. Understanding the distinction between these two is crucial for robust and efficient Java programming.
| Aspect | Checked Cases | Unchecked Cases |
|---|---|---|
| Definition | Any case which must be handled or caught while writing the program is called checked. | Any case which is not mandatory to handle or catch while writing or executing the program is called unchecked. |
| Example | 1. FileNotFoundException: FileReader file = new FileReader(“file.txt”); 2. IOException: InputStream input = new FileInputStream(“input.txt”); | 1. NullPointerException: Employee e1 = null; System.out.println(e.name); 2. ArrayIndexOutOfBounds: int a[] = new int[10]; System.out.println(a[20]); |
| Hierarchy | They are all subclasses of the Exception class. | They are all subclasses of the RuntimeException class. |
| Ignorance | Must be formally acknowledged in the program one way or another. | Can be ignored completely in the code if desired. |
| Compilation | If your code fails to either handle a checked case or declare that it is thrown, your code won’t compile. | If your code fails to either handle an Unchecked case or declare that it is thrown, your code will compile. |
| Handling Verification | Checked cases in Java are those whose handling is verified during Compile time. | Unchecked cases in Java are those whose handling is not verified during Compile time. |
| JVM | JVM enforces the developer to handle or catch checked cases. | JVM does not enforce the developer to handle or catch unchecked cases. |
| Propagation | By default, Checked cases are not forwarded in the calling chain (propagated). | By default Unchecked cases are forwarded in the calling chain (propagated). |
| Caught/Uncaught | They are also called as caught cases. | They are also called as uncaught cases. |
| Throws Clause | The throws clause on a method header must be included for checked cases that are not caught and handled in the method. | The throws clause on a method header is not mandatory to be included for unchecked cases that are not caught and handled in the method. |
| Scenario | Checked cases represent scenarios with a higher failure rate. | Unchecked cases are mostly programming errors. |
| Use | Example scenarios: – File reading error when the file is deleted before the operation begins, anticipating this failure for the user to try another filename. – Business logic validation error, such as dividing a number by zero. | Example scenarios: – Upload failure due to network loss, anticipating this failure for the user to attempt another upload or resume from where it stopped.- User input validation error when a non-digit is entered instead of a digit. |
Conclusion
Finally, understanding and managing exceptions, both checked and unchecked, is vital to becoming adept at Java programming. These skill sets enable developers to predict, capture, and handle potential errors during the code execution, ensuring the creation of reliable and error-resistant applications. Remember, effective error handling improves not only the robustness but also the readability of your code, ultimately making you a better Java programmer. If you’re looking to enhance your Java programming skills, it’s advisable to delve deeper into the concept of blocks in Java.