{"id":18380,"date":"2018-06-13T04:10:33","date_gmt":"2018-06-13T04:10:33","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=18380"},"modified":"2021-12-04T10:15:22","modified_gmt":"2021-12-04T04:45:22","slug":"scala-throw-keyword","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/scala-throw-keyword\/","title":{"rendered":"How Can We Use Scala Throw Keyword – Scala Exception"},"content":{"rendered":"

In this tutorial, we will talk about the Scala Throw Keyword. So, in this\u00a0Scala\u00a0Throw\u00a0keyword\u00a0Tutorial, we are going to see how can we Throw Custom Exception in Scala Programming Language<\/strong><\/a>. Moreover, we will discuss\u00a0Catching Exceptions in Scala.<\/p>\n

Let\u2019s begin Sacla Throw Keyword.<\/p>\n

\"How<\/a>

How Can We Use Scala Throw Keyword – Scala Exception<\/p><\/div>\n

How Can We Throw Custom Exceptions in Scala?<\/h3>\n

Scala lets you create your own custom exceptions using the Scala Throw Keyword. With this, you can explicitly throw an exception in your code.
\nLet’s Get a Clear Information About Scala Exceptions and Exception Handling<\/a><\/strong>
\nLet\u2019s take a simple example.<\/p>\n

scala> def person(age:Int){\r\n| if(age!=15)\r\n| throw new Exception(\"Wait a little\")\r\n| else println(\"Enjoy your quinceanera\")\r\n| }\r\nperson: (age: Int)Unit\r\nscala> person(15)<\/pre>\n
Enjoy your quinceanera<\/p>\n
scala> person(14)<\/pre>\n
java.lang.Exception: Wait a little<\/p>\n
at .person(<console>:13)\r\n... 28 elided<\/pre>\n
Scala Throw Keyword<\/h3>\n
Now, when we know a method can throw an exception, we may want to tell Scala. We use the Scala throws keyword for this, but we can also place the @throws annotation right before a method.<\/p>\n
@throws(classOf[Exception])\r\noverride def play{\r\n\/\/exception-throwing code\r\n}<\/pre>\n
But a method may throw more than one code. To mention all of these, we use multiple annotations in Scala<\/strong><\/a>.<\/p>\n
@throws(classOf[IOException])\r\n@throws(classOf[LineUnavailableException])\r\n@throws(classOf[UnsupportedAudioFileException])\r\ndef playSoundFileWithJavaAudio{\r\n\/\/exception-throwing code\r\n}<\/pre>\n
@throws is also a way to provide the method signature for \u2018throws\u2019 to those who work with Java Programming Language<\/strong><\/a>. Java would have the following code for this:<\/p>\n
public void play() throws FooException{\r\n\/\/code\r\n}<\/pre>\n
Do you Know 2 Popular Types of Constructors in Scala<\/a><\/strong><\/p>\n
More On Throw Keyword in Scala<\/h3>\n
Talking about checked exceptions, Scala doesn\u2019t need methods to declare that they can throw exceptions. In Scala, all exceptions are RuntimeException<\/i>s, and it is the developer who must decide when to handle them. It doesn\u2019t force us to handle these exceptions.<\/p>\n
scala> def demo{\r\n| throw new Exception\r\n| }<\/pre>\n
demo: Unit
\nWe don\u2019t even need to call these methods to catch the exceptions.<\/p>\n
scala> demo\r\njava.lang.Exception\r\nat .demo(<console>:12)\r\n... 28 elided<\/pre>\n
But we must test for them if we want our code to work fine:<\/p>\n
scala> object Demo extends App{\r\n| def demo{\r\n| throw new Exception}\r\n| println(\"After demo\")\r\n| demo\r\n| \/\/Code never executed\r\n| println(\"After demo\")\r\n| }<\/pre>\n
defined object Demo
\nRead about Scala Regular Expressions \u2013 Replacing Matches<\/a><\/strong><\/p>\n
Catching Exceptions in Scala<\/h3>\n
In the following example, we throw an exception and then have a wildcard pattern case catch it. This pattern catches any exception of the kind throwable.<\/p>\n
scala> try{\r\n| throw new Exception(\"Failed\")\r\n| } catch{\r\n| \/\/catching all Throwable exceptions\r\n| case _:Throwable=>println(\"An exception occurred\")\r\n| }<\/pre>\n
An exception occurred<\/p>\n
Example- Exceptions With Pattern Matching<\/h3>\n
Let\u2019s take another example. Here, we combine pattern-matching<\/strong> <\/a>with exception handling<\/strong><\/a>. This is a bit like the previous example.<\/p>\n
scala> import java.net.URL\r\nimport java.net.URL\r\nscala> import java.net.MalformedURLException\r\nimport java.net.MalformedURLException\r\nscala> import java.io.IOException\r\nimport java.io.IOException\r\nscala> try{\r\n| val url=new URL(\"http:\/\/data-flair.training\")\r\n| }catch{\r\n| case e:MalformedURLException=>println(\"Bad URL \"+e)\r\n| case e:IOException=>println(\"An IO issue \"+e)\r\n| case _:Throwable=>println(\"Something else\")\r\n| }finally{\r\n| \/\/cleanup\r\n| }<\/pre>\n
Let’s Explore Scala Singleton & Scala Companion Object<\/a><\/strong>
\nSo, this was all about Scala Throw Keyword. Hope you like our explanation.<\/p>\n
Conclusion<\/h3>\n
Hence, in this Scala Throw tutorial, we have seen how we can throw custom exceptions in Scala. Drop your queries in the comments.
\nRelated Topic-\u00a0\u00a0How to Implement Scala Abstract Class with Examples<\/a><\/strong>
\nFor reference<\/a><\/strong>
In this tutorial, we will talk about the Scala Throw Keyword. So, in this\u00a0Scala\u00a0Throw\u00a0keyword\u00a0Tutorial, we are going to see how can we Throw Custom Exception in Scala Programming Language. Moreover, we will discuss\u00a0Catching Exceptions...<\/p>\n","protected":false},"author":6,"featured_media":18398,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61],"tags":[12408,12440,12441,12543,12561,12562,12563,12564,12565],"class_list":["post-18380","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scala","tag-scala-catch-exception","tag-scala-exception-handling","tag-scala-exception-types","tag-scala-rethrow-exception","tag-scala-throw-checked-exception","tag-scala-throw-exception-in-match","tag-scala-throw-keyword","tag-scala-throw-runtime-exception","tag-scala-throws-exception"],"yoast_head":"\nHow Can We Use Scala Throw Keyword - Scala Exception - DataFlair<\/title>\n<meta name=\"description\" content=\"Scala Throw Keyword tutorial-Throw Custom Exceptions in Scala,Can We Checked Excpetion Throw Keyword in Scala,Example of Exceptions With Pattern Matching\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/data-flair.training\/blogs\/scala-throw-keyword\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How Can We Use Scala Throw Keyword - 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