Difference Between Checked and Unchecked Exception (With Table)

Checking for exceptions is one of the most important things in programming and software testing. Checked And Unchecked Exception stops the program from running when it is trying to catch a bug or error. Moreover, it is considered as it is the programmer’s responsibility to make sure these errors never happen. Both Checked and Unchecked Exception is exceptionally similar, yet they are different from each other.

Checked vs Unchecked Exception

The difference between Checked And Unchecked Exception is that Checked exceptions are those that must be caught and handled by the checks () statement or they will cause a program to terminate and print a stack trace, whereas, Unchecked exceptions, on the other hand, should not need to be caught or handled at all, as it is the programmer’s responsibility to make sure these errors never happen.

The Checked exception is a specific type of exception that stops the program from running until it is either caught by a catch block or specified in the throws clause of a method, moreover, Checked exception is caught and handled by the checks () statement or they will cause a program to terminate and print a stack trace.

If the code that caused the exception was not tested properly, it could cause strange Unchecked exceptional bugs that can be difficult to find and fix. Moreover, Unchecked exceptions should not need to be caught or handled at all, as it is the programmer’s responsibility to make sure these errors never happen.

Comparison Table Between Checked and Unchecked Exception

Parameters of ComparisonChecked ExceptionUnchecked Exception
DefinitionChecked exceptions are those that must be caught and handled by the checks () statements.Unchecked Exceptions should not need to be caught or handled at all.
OccurrenceChecked exceptions must be handled by a catch block during compile time. Uncaught exceptions also known as runtime exceptions are Unchecked Exceptions.
Error HandlingChecked Exception stops the program from running until is trying to catch a bug or error. It is the programmer’s responsibility to make sure these errors never happen.
Exception ClassesIt does have exceptional classes.It does not have any exceptional classes or it is not a major part of exceptional classes.
ExampleOutOfMemoryError, NullPointerException and StackOverflowError.IndexOutOfBoundsException

What is Checked Exception?

Checked Exceptions are closely related to software testing, moreover, a checked exception is an exception that must be handled, or the program will terminate. This means that code following a throw statement will not execute if no catch block handles the exception. Checked exceptions serve two purposes that are they stop the program from continuing when an error has occurred, and they can provide debugging information about where to find that error.

The compiler does not force the programmer to handle the exception, but any class that extends another class should also either extend or implement all of its checked exceptions. If it does not, a compilation of the extending class fails with a compile-time error stating that it must handle all of its superclass-checked exceptions. This prevents inheritance from being used to circumvent built-in failure modes.

When an exception is thrown, it is passed to the debugger in Eclipse or to the operating system, which then terminates the program normally. The operating system prints out a stack trace. A stack trace provides information for each method call in the order they were called. This allows the programmer to find where in code or where in their code’s execution flow an exception occurred.

What is Unchecked Exception?

Unchecked exceptions exist to allow programmers to program more flexibly and efficiently. Java has been designed to enable programmers to create applications that use resources efficiently and avoid the appearance of deadlock. Unchecked exceptions can be eliminated by careful design and coding practices. However, all other exceptions except NullPointerException that occur in Java code are considered unchecked.

Unchecked exceptions should not need to be caught or handled at all. Moreover, They are a way for higher-level code to tell lower-level code that it is going to do something that is not thread-safe, but that will not cause problems if there is only one thread running at any given time, such as updating some data or rendering some graphics on the screen.

Using unchecked exceptions is a risky proposition. If a class is going to throw an unchecked exception, then who uses that class needs to be aware of it and have some rigorous methods in place for dealing with it. For example, a programmer may want to read some data from a file and then write it back again, and this kind of functionality does not need any synchronization. It’s perfectly acceptable for an application to read the same data twice on two different threads without having any negative effects on system performance or stability.

Main Differences Between Checked and Unchecked Exception

  1. Checked Exceptions are those that must be caught and handled by the checks () statements, whereas, Unchecked Exceptions should not need to be caught or handled at all.
  2. Checked Exceptions must be handled by a catch block during compile time, whereas, Uncaught Exceptions also known as runtime exceptions are Unchecked Exceptions.
  3. Checked Exception stops the program from running until it is trying to catch a bug or error, whereas, Unchecked Exceptions is the programmer’s responsibility to make sure these errors never happen.
  4. Checked Exception does have exceptional classes, whereas, Unchecked Exceptions does not have any exceptional classes or it is not a major part of exceptional classes.
  5. An example of a Checked Exception would be an OutOfMemoryError, NullPointerException, and StackOverflowError whereas, an example of an Unchecked Exception would be an IndexOutOfBoundsException.

Conclusion

A Checked exception is an exception that must be handled, or the program will terminate. However, Unchecked exceptions are those which execute stop functions for all threads. A Checked And Unchecked Exception is a signal of a failure in code. This happens when the code is trying to do something unexpected. If the code that caused the exception was not tested properly, it could cause strange bugs that can be difficult to find and fix. In some cases, the programmer may even need to rewrite the entire program from scratch. Moreover, Checked And Unchecked Exceptions are closely related to software testing.

References

  1. https://ieeexplore.ieee.org/abstract/document/4343929/
  2. https://link.springer.com/article/10.1023/A:1010020917337
  3. https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.90.1517&rep=rep1&type=pdf
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