Scala break statement

Scala cycle

Scala language default is no break statement, but you can use another way after Scala 2.8 version to achievebreakstatement. When using thebreak statement in a loop when executing to this statement, it will break the cycle and execute the code block after the loop.

grammar

Scala syntax in the break a little less like the following format:

// 导入以下包
import scala.util.control._

// 创建 Breaks 对象
val loop = new Breaks;

// 在 breakable 中循环
loop.breakable{
    // 循环
    for(...){
       ....
       // 循环中断
       loop.break;
   }
}

flow chart

Examples

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" );
   }
}

Execute the above code output results:

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

Interrupt nesting loop

The following example demonstrates how to break 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;
                  }
               }
            } // 内嵌循环中断
         }
      } // 外部循环中断
   }
}

Execute the above code output results:

$ 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 cycle