返回一个只包含1个指定元素的列表，相对于AsList()，它优化了内存分配

	List<Map<String, Object>> srcNodeMapResult = Collections.singletonList(nodeMap)
      
  	// srcNodeMapResult此时只对应了1个源节点的属性集，因此在单源条件下，将List转变成singletonList节省内存

具体示例

import java.util.*;

public class CollectionsDemo {
     public static void main(String args[]) {
      // create an array of string objs
      String init[] = { "One", "Two", "Three", "One", "Two", "Three" };
      
      // create one list
      List list = new ArrayList(Arrays.asList(init));
      
      System.out.println("List value before: "+list);
      
      // create singleton list
      list = Collections.singletonList("TP");
      
      System.out.println("List value after: "+list);
   }
}

输出结果

List value before: [One, Two, Three, One, Two, Three]
List value after: [TP]