斯卡拉 |产量关键字

yield关键字将在循环迭代完成后返回结果。 for 循环在内部使用缓冲区来存储迭代结果，当完成所有迭代时，它会从该缓冲区产生最终结果。它不像命令式循环那样工作。返回的集合的类型与我们倾向于迭代的类型相同，因此 Map 产生一个 Map，一个 List 产生一个 List，依此类推。

句法：

var result = for{ var x Note: The curly braces have been used to keep the variables and conditions and result is a variable wherever all the values of x are kept within the form of collection.Example:// Scala program to illustrate yield keyword  // Creating objectobject GFG {     // Main method    def main(args: Array[String])     {         // Using yield with for        var print = for( i <- 1 to 10) yield i         for(j<-print)        {             // Printing result            println(j)         }     } } Output:1
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10In above example, the for loop used with a yield statement actually creates a sequence of list.Example:// Scala program to illustrate yield keyword  // Creating objectobject GFG {     // Main method    def main(args: Array[String])     {         val a = Array( 8, 3, 1, 6, 4, 5)                  // Using yield with for        var print=for (e <- a if e > 4) yield e        for(i<-print)        {             // Printing result            println(i)         }     } } Output:8
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5In above example, the for loop used with a yield statement actually creates a array. Because we said yield e, it’s a Array[n1, n2, n3, ....]. e  is our generator and if (e > 4) could be a guard that filters out number those don't seem to be greater than 4.