How do I create a custom exception in Scala?
Scala Custom Exception Example
- class InvalidAgeException(s:String) extends Exception(s){}
- class ExceptionExample{
- @throws(classOf[InvalidAgeException])
- def validate(age:Int){
- if(age<18){
- throw new InvalidAgeException(“Not eligible”)
- }else{
- println(“You are eligible”)
How do you handle exceptions in Scala?
try/catch/finally
A basic way we can handle exceptions in Scala is the try/catch/finally construct, really similar to the Java one. In the following example, to make testing easier, we’ll return a different negative error code for each exception caught: def tryCatch(a: Int, b: Int): Int = { try { return Calculator.
How do you use throws in Scala?
Scala provides throws keyword to declare exception. You can declare exception with method definition. It provides information to the caller function that this method may throw this exception. It helps to caller function to handle and enclose that code in try-catch block to avoid abnormal termination of program.
What is try in Scala?
The Try type represents a computation that may either result in an exception, or return a successfully computed value. It’s similar to, but semantically different from the scala. util. Either type. Instances of Try[T] , are either an instance of scala.
How can you create custom exception?
Steps to create a Custom Exception with an Example
- CustomException class is the custom exception class this class is extending Exception class.
- Create one local variable message to store the exception message locally in the class object.
- We are passing a string argument to the constructor of the custom exception object.
How do you create an exception?
To create the exception object, the program uses the throw keyword followed by the instantiation of the exception object. At runtime, the throw clause will terminate execution of the method and pass the exception to the calling method.
How do you do a try catch in Scala?
Scala Try Catch Example
- class ExceptionExample{
- def divide(a:Int, b:Int) = {
- try{
- a/b.
- }catch{
- case e: ArithmeticException => println(e)
- }
- println(“Rest of the code is executing…”)
What is Monad in Scala?
In Scala, Monads is a construction which performs successive calculations. It is an object which covers the other object. It is worth noting that here, the output of an operation at some step is an input to another computations, which is a parent to the recent step of the program stated.
What is throwable Scala?
Throwable is just an alias for java. lang. Throwable . So in Scala, a catch clause that handles Throwable will catch all exceptions (and errors) thrown by the enclosed code, just like in Java.
How do you use try and catch in Scala?
Scala Try Catch
- class ExceptionExample{
- def divide(a:Int, b:Int) = {
- try{
- a/b.
- }catch{
- case e: ArithmeticException => println(e)
- }
- println(“Rest of the code is executing…”)
Is Scala try a Monad?
The Scala Try class was introduced as a monadically-composable mechanism for exception handling in Scala 2.10 and back-ported to Scala 2.9. 3. The ways that this class interacts with the Monad Laws has been a subject of some discussion in the Scala community.
What is for yield in Scala?
Summary: Scala’s ‘yield’ keyword
For each iteration of your for loop, yield generates a value which is remembered by the for loop (behind the scenes, like a buffer). When your for loop finishes running, it returns a collection of all these yielded values.
What is a custom exception?
Custom exceptions provide you the flexibility to add attributes and methods that are not part of a standard Java exception. These can store additional information, like an application-specific error code, or provide utility methods that can be used to handle or present the exception to a user.
Can we create custom runtime exception?
We can create the custom unchecked exception by extending the RuntimeException in Java. Unchecked exceptions inherit from the Error class or the RuntimeException class.
Is it good to have nested try catch?
Why you should care. Although this is sometimes unavailable, nesting try/catch blocks severely impacts the readability of the source code as it makes it difficult to understand which block will catch which exception.
What is currying in Scala?
Currying is the process of converting a function with multiple arguments into a sequence of functions that take one argument. Each function returns another function that consumes the following argument.
What is cats in Scala?
Cats is a library which provides abstractions for functional programming in the Scala programming language. Scala supports both object-oriented and functional programming, and this is reflected in the hybrid approach of the standard library.
What is difference between throwable and exception?
Throwable is super class of Exception as well as Error . In normal cases we should always catch sub-classes of Exception , so that the root cause doesn’t get lost. Only special cases where you see possibility of things going wrong which is not in control of your Java code, you should catch Error or Throwable .
What are the three useful methods of throwable?
Three useful methods of the Throwable class that provide information about an exception are the following: getMessage (): Returns the message that was encapsulated when the object was initiated. It returns null, if there is no message. toString(): returns a brief description about the exception of throwable object.
How do you write a try catch block Scala?
Is Scala future a monad?
yes, then it’s a monad. @ElectricCoffee no. @PabloFernandez Scala’s flatMap is Haskell’s >>= , and Scala’s for-comprehensions are equivalent to Haskell’s do notation.
What is monads in Scala?
What does => mean in Scala?
=> is syntactic sugar for creating instances of functions. Recall that every function in scala is an instance of a class. For example, the type Int => String , is equivalent to the type Function1[Int,String] i.e. a function that takes an argument of type Int and returns a String .
Why yield is used in Scala?
Yield is a keyword in scala that is used at the end of the loop. We can perform any operation on the collection elements by using this for instance if we want to increment the value of collection by one. This will return us to the new collection.