Scala Map retain() 方法与示例

retain()方法用于保留满足所述条件的所有映射对。

Method Definition: def retain(p: (A, B) => Boolean): Map.this.type

Return Type: It returns all the “key-value” pairs of the map which satisfies the stated predicate.

示例 #1：

// Scala program of retain()
// method
  
// Creating object
object GfG
{ 
  
    // Main method
    def main(args:Array[String])
    {
      
        // Creating a mutable map
        val m1 = scala.collection.mutable.Map(3 -> "geeks", 
                                    1 -> "for", 2 -> "cs")
          
        // Applying retain method
        val result = m1.retain((key,value) => key > 1)
          
        // Displays output
        println(result)
      
    }
}

输出：

Map(2 -> cs, 3 -> geeks)

示例：2#

// Scala program of retain()
// method
  
// Creating object
object GfG
{ 
  
    // Main method
    def main(args:Array[String])
    {
      
        // Creating a mutable map
        val m1 = scala.collection.mutable.Map(3 -> "geeks",
                                    1 -> "for", 1 -> "cs")
          
        // Applying retain method
        val result = m1.retain((key,value) => key > 1)
          
        // Displays output
        println(result)
          
    }
}

输出：

Map(3 -> geeks)