Scala Map filter() 方法与示例

filter()方法用于选择满足指定谓词的映射的所有元素。

Method Definition: def filter(p: ((A, B))=> Boolean): Map[A, B]

Return Type: It returns a new map consisting all the elements of the map which satisfies the given predicate.

示例 #1：

// Scala program of filter()
// method
  
// Creating object
object GfG
{ 
  
    // Main method
    def main(args:Array[String])
    {
      
        // Creating map
        val m1 = Map("geeks" -> 5, "for" -> 3)
          
        // Applying filter method
        val result = m1.filter(x => x._1 == "geeks" && x._2 == 5)
          
        // Displays output
        println(result)
      
    }
}

输出：

Map(geeks -> 5)

示例 #2：

// Scala program of filter()
// method
  
// Creating object
object GfG
{ 
  
    // Main method
    def main(args:Array[String])
    {
      
        // Creating map
        val m1 = Map("geeks" -> 5, "for" -> 3)
          
        // Applying filter method
        val result = m1.filter(x => x._1 == "for" && x._2 == 5)
          
        // Displays output
        println(result)
      
    }
}

输出：

Map()

此处，由于没有元素满足所述谓词，因此返回一个空映射。