Scala Tutorial - Scala try expressions

Exception handling in Scala is implemented differently, but it behaves exactly like Java and works seamlessly with existing Java libraries.

All exceptions in Scala are unchecked; there is no concept of checked exception.

Throwing exceptions is the same in Scala and Java.

throw new Exception("some exception...")

The try/finally construct is also the same in Scala and Java as shown in the following code.

try {
 throw newException("some exception...")
} finally{
 println("This will always be printed")
}

try/catch in Scala is an expression that results in a value.

The exception in Scala can be pattern matched in the catch block instead of providing a separate catch clause for each different exception.

Because try/catch in Scala is an expression, it becomes possible to wrap a call in a try/catch and assign a default value if the call fails.

The following code shows a basic try/catch expression with pattern matched catch block.

try {
 file.write(stuff)
} catch{
 case e:java.io.IOException => // handle IO Exception
 case n:NullPointerException => // handle null pointer
}

Example

The following code shows an example of wrapping a call in try/catch by calling Integer.parseIntand assigning a default if the call fails.

try{
 Integer.parseInt("dog")
}catch{
 case_ => 0
}