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This article mainly explains "what are the methods of dealing with exceptions in Java". The content of the explanation in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn what are the methods of handling exceptions in Java.

I. Classification of anomalies

Throwable is the superclass of all exceptions, and the next level can be divided into Error and Exception:

1. Error

Error refers to the errors within the Java runtime system, or it represents the errors of JVM itself, which are usually serious errors, such as memory overflow, virtual machine errors, and so on; Error is usually related to hardware or JVM, and has nothing to do with the program itself, so it cannot be captured and processed by code.

2. Exception

The exception we often refer to is Exception, which can be divided into run-time exceptions and check exceptions.

RuntimeException: runtime exceptions, which do not force code capture during compilation, but may be thrown during JVM run; such exceptions are usually a problem with the code, so you need to modify the program to avoid such exceptions. Common runtime exceptions, such as NullPointerException, ClassCastException, and so on.

CheckedException: check for exceptions that occur during compilation, and the Java compiler forces the code to catch and handle such exceptions; for example, ClassNotFoundException, IllegalAccessException, and so on.

Second, the handling method of exception

Catch an exception using the try...catch statement, put the code that may cause an exception into try {...}, and then use catch to catch the corresponding exception; we can also use Throw in the code block to throw an exception to the parent code; use the throws keyword in the method to throw an exception to the parent code

III. The difference between Throw and throws

Throw is in a method, followed by an exception object, while throws is used in a method, followed by an exception class

Throw throws a specific exception object, and when the execution reaches Throw, the code in the method ends execution. Throws is used to declare an exception and remind the caller that such an exception may occur in this method. Be prepared to handle it, but the exception may not occur.

IV. Some suggestions on using Exception

1. Do not try to control the program flow through exceptions, such as developing an interface, the correct thing to do is to validate the input parameters without null, and return "parameters are not allowed to be null" when the parameters are null. You should not return an error prompt when a null pointer is caught.

two。 Capture only the necessary code, and try not to use a single try...catch to wrap all the code in a large segment or even the entire method, as this will affect JVM to optimize the code, resulting in additional performance overhead.

3. Many programmers like catch (Exception e), but they should point out what the exception is as precisely as possible.

4. Do not ignore the exception, do not do nothing after catching the exception, either output the exception information in catch {...}, or throw the exception through Throw or throws and let the upper code handle it.

5. Try not to throw an exception after outputting an exception in catch {.}, because this will output multiple exception messages, and they are the same, which may be misleading.

6. Do not write return in finally {...} because try {...} executes finally {...} before executing return, and if there is a return in finally {...}, then return in try {...} will no longer be executed.

Thank you for your reading, the above is the content of "what are the methods of handling exceptions in Java". After the study of this article, I believe you have a deeper understanding of what the methods of handling exceptions in Java have, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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