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Scala exceptions work like exceptions in many other languages such as Java. Instead of returning a value in a normal way, the method can be terminated by throwing an exception. However, Scala does not actually check for exceptions. When you want to handle exceptions, you can use try {... as you would in Java. } catch {... } blocks, except that catch blocks use matching to identify and handle exceptions.

Scala's exception handling is similar to other languages such as Java. Scala's method can terminate the execution of the relevant code by throwing an exception, without having to return a value.

Throw an exception

Scala throws an exception in the same way as Java, using the throw method, for example, throwing a new parameter exception:

Throw new IllegalArgumentException catch exception

The mechanism of exception catching is the same as in other languages. If an exception occurs, catch sentences are caught sequentially. Therefore, in the catch sentence, the more specific exception is, the more common the exception is, the lower the exception is. If the exception thrown is not in the catch sentence, the exception cannot be handled and will be escalated to the caller.

Catch exception catch clause, syntax is not quite the same as in other languages. In Scala, the idea of pattern matching is borrowed to do abnormal matching, so in the code of catch, there is a series of case sentences, as shown in the following example:

Import java.io.FileReaderimport java.io.FileNotFoundExceptionimport java.io.IOExceptionobject Test {def main (args: Array [String]) {try {val f = new FileReader ("input.txt")} catch {case ex: FileNotFoundException = > {println ("Missing file exception")} case ex: IOException = > {println ("IOException")}

Execute the above code, and the output is as follows:

$scalac Test.scala$ scala TestMissing file exception

The content in the catch sentence is exactly the same as the case in match. Because exceptions are caught sequentially, if the most common exception, Throwable, is written first, it cannot be caught by the case after it, so you need to write it at the end.

Finally statement

The finally statement is used to perform steps that need to be performed regardless of normal processing or when an exception occurs. Examples are as follows:

Import java.io.FileReaderimport java.io.FileNotFoundExceptionimport java.io.IOExceptionobject Test {def main (args: Array [String]) {try {val f = new FileReader ("input.txt")} catch {case ex: FileNotFoundException = > {println ("Missing file exception")} case ex: IOException = > {println ("IOException")} finally { Println ("Exiting finally...")}

Execute the above code, and the output is as follows:

$scalac Test.scala$ scala TestMissing file exceptionExiting finally... The above is the content of this article on "what is the Scala exception handling method". I believe we all have a certain understanding. I hope the content shared by the editor will be helpful to you. If you want to know more about the relevant knowledge, please follow the industry information channel.

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