Scala Break Statement

Scala Loop Types

In Scala, there is no default break statement, but you can achieve a similar effect using a different approach since version 2.8. When a break statement is used within a loop, the loop is interrupted and the code block following the loop is executed.

Syntax

The syntax for break in Scala is somewhat different, as follows:

// Import the following package
import scala.util.control._

// Create a Breaks object
val loop = new Breaks;

// Loop within breakable
loop.breakable{
    // Loop
    for(...){
       ....
       // Loop interruption
       loop.break;
   }
}

Flowchart

Example

import scala.util.control._

object Test {
   def main(args: Array[String]) {
      var a = 0;
      val numList = List(1,2,3,4,5,6,7,8,9,10);

      val loop = new Breaks;
      loop.breakable {
         for( a <- numList){
            println( "Value of a: " + a );
            if( a == 4 ){
               loop.break;
            }
         }
      }
      println( "After the loop" );
   }
}

The output of the above code is:

$ scalac Test.scala
$ scala Test
Value of a: 1
Value of a: 2
Value of a: 3
Value of a: 4
After the loop

Interrupting Nested Loops

The following example demonstrates how to interrupt nested loops:

import scala.util.control._

object Test {
   def main(args: Array[String]) {
      var a = 0;
      var b = 0;
      val numList1 = List(1,2,3,4,5);
      val numList2 = List(11,12,13);

      val outer = new Breaks;
      val inner = new Breaks;

      outer.breakable {
         for( a <- numList1){
            println( "Value of a: " + a );
            inner.breakable {
               for( b <- numList2){
                  println( "Value of b: " + b );
                  if( b == 12 ){
                     inner.break;
                  }
               }
            } // Inner loop interruption
         }
      } // Outer loop interruption
   }
}

The output of the above code is:

$ scalac Test.scala
$ scala Test
Value of a: 1
Value of b: 11
Value of b: 12
Value of a: 2
Value of b: 11
Value of b: 12
Value of a: 3
Value of b: 11
Value of b: 12
Value of a: 4
Value of b: 11
Value of b: 12
Value of a: 5
Value of b: 11
Value of b: 12

Scala Loop Types