如何从 Map 中获取多个随机值？ - 飞镖

Question

我试图从map 中获取一些随机的多个值作为列表，代码中有一些解释 //，任何逻辑如果 Function 或喜欢我的逻辑，在此先感谢

   class Test{
      String url;
      int id;
      String name;
      Test({required this.url , required this.id , required this.name});
    }
    
    class Fake{
      static List<Test> getSomeValues = [
        Test(id: 1 , url : "test/test" , name : "1Name"),
        Test(id: 2 , url : "test/test" , name : "2Name"),
        Test(id: 3 , url : "test/test" , name : "3Name"),
      ]; 
    }
    
    void widget(Test t){
      print(t.id);
      
    }
    
    void main(){
      print(Fake.getSomeValues.asMap().entries.where((f){
        // here just I can apply condition on each Value can't get random 
        return f.value.id == 1 ; 
        
      }).map((f){
         // I don't want not needy value arrive here .
        // after I want to use each instance of Test . 
        return widget(f.value);
      }).toList());
    }

例如输出：

void getRandom(List<test> t , int count){
// code
print(t.id)
}
getRandom(test , 2),

输出：

3,1 

Answer 1

请检查

import 'dart:math';

class Test{
      String url;
      int id;
      String name;
      Test({this.url ,  this.id ,  this.name});
    }
    
    class Fake{
      static List<Test> getSomeValues = [
        Test(id: 1 , url : "test/test" , name : "1Name"),
        Test(id: 2 , url : "test/test" , name : "2Name"),
        Test(id: 3 , url : "test/test" , name : "3Name"),
        Test(id: 4 , url : "test/test" , name : "4Name"),
        Test(id: 5 , url : "test/test" , name : "5Name"),
        Test(id: 6 , url : "test/test" , name : "6Name"),
        Test(id: 7 , url : "test/test" , name : "7Name"),
      ]; 
    }
    
    
    
    void main(){
     List<Test>  itemOfList= shuffle(Fake.getSomeValues, 3);
      itemOfList.forEach((e)=> print(e.name));
    }

List<Test> shuffle(List<Test> items, int item) {
  var random = new Random();

  items.shuffle();

  return items.sublist(0, item);
}