The Difference between Checked and Unchecked Exceptions
Exceptions are a common aspect of programming in Java. They are thrown when a program encounters an error, making it possible for developers to handle these errors and prevent their programs from crashing. Java exceptions can be divided into two categories – checked and unchecked exceptions. In this article, we will discuss the differences between these two types of exceptions.
Checked Exceptions
Checked exceptions are those exceptions that are checked during compile-time. This means that the Java compiler will throw an error if the code does not have the necessary measures in place to handle these exceptions. A checked exception is a subclass of the Exception class, and it must conform to certain rules, such as being declared in the method signature or surrounded by a try-catch block.
A common example of a checked exception is FileNotFoundException. If a program attempts to open a file that does not exist, this exception will be thrown. The developer must handle this exception by using try-catch blocks or by throwing the exception up the call-stack to another method that can handle the exception.
Unchecked Exceptions
Unchecked exceptions are those exceptions that are not checked during compile-time. The Java compiler will not throw an error if the code does not have the necessary measures in place to handle these exceptions. Unchecked exceptions are subclasses of the RuntimeException class, and they do not need to be declared in a method signature.
A common example of an unchecked exception is NullPointerException. If a program tries to access an object or variable that has not been assigned a value, this exception will be thrown. The developer does not need to handle this exception, although it is still best practice to write code in such a way that these exceptions are avoided.
The Key Differences
The main difference between checked and unchecked exceptions is that checked exceptions are checked during compile-time, and they must be declared or handled. Unchecked exceptions, on the other hand, are not checked during compile-time, and they do not require declaration or handling.
Another key difference is how these exceptions are handled. In the case of checked exceptions, the developer must handle the exception by using try-catch blocks or by throwing the exception up the call-stack. With unchecked exceptions, the developer can choose to handle them or not.
Conclusion
In conclusion, when writing Java code, it is important to understand the difference between checked and unchecked exceptions. While both types of exceptions serve the same purpose of handling errors, their handling and declaration differ. Being able to handle these exceptions efficiently can help developers create better, more robust software.
Table difference between checked and unchecked exceptions
| Checked Exceptions | Unchecked Exceptions |
|---|---|
|
Checked exceptions are checked by the compiler at compile time. Programmers are required to handle checked exceptions at compile time. They can be handled by either:
Examples of checked exceptions include |
Unchecked exceptions are not checked by the compiler at compile time. Programmers are not required to handle unchecked exceptions at compile time. They can be handled at run time. Examples of unchecked exceptions include |
|
Checked exceptions are used for conditions that can be recovered from without terminating the program. They are usually caused by user errors or I/O problems. |
Unchecked exceptions are used for conditions that can not be recovered from without terminating the program. They are usually caused by programming errors or unexpected system conditions. |