Scala break Statement

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As such there is no built-in break statement available in Scala but if you are running Scala version 2.8, then there is a way to use break statement. When the break statement is encountered inside a loop, the loop is immediately terminated and program control resumes at the next statement following the loop.

Syntax:

The syntax of a break statement is bit unusual but it works:

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

// create a Breaks object as follows
val loop = new Breaks;

// Keep the loop inside breakable as follows
loop.breakable{
    // Loop will go here
    for(...){
       ....
       // Break will go here
       loop.break;
   }
}

Flow Diagram:

Scala break statement

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" );
   }
}

When the above code is compiled and executed, it produces the following result:

C:/>scalac Test.scala
C:/>scala Test
Value of a: 1
Value of a: 2
Value of a: 3
Value of a: 4
After the loop

C:/>

Breaking Nested Loops:

Existing break has an issue while using for nested loops. So in case you have to use break for nested loops, then following is a way to proceed:

Example:

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 breakable
         }
      } // outer breakable.
   }
}

When the above code is compiled and executed, it produces the following result:

C:/>scalac Test.scala
C:/>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

C:/>


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