We use where() method with collections (like list, set ..) to filter out that collection elements. A where() method returns a new iterable which satisfies the condition in the where() method.

What we want to do is that we will take a list of students with their name and age. Will take a searching parameter to filter out students. Let’s see the code to filter out element from a list of maps using where() method:

void main() {
  var list1 = [
    {
      "Name": "Harry Potter",
      "Age": "14"
    },
    {
      "Name": "Ginny Weasly",
      "Age": "13"
    },
    {
      "Name": "Ron Weasly",
      "Age": "14"
    }
  ];

  print("All students : ");
  print(list1);
  
  String searchingStr = "Weasly";
  
  var filteredList = list1.where( (student)=>
    student["Name"]!.contains(searchingStr) || 
    student["Age"]!.contains(searchingStr)
  );
  
  print("Searched students : ");
  print(filteredList.toList());
}

Output :
All students :
[{Name: Harry Potter, Age: 14}, {Name: Ginny Weasly, Age: 13}, {Name: Ron Weasly, Age: 14}]
Searched students :
[{Name: Ginny Weasly, Age: 13}, {Name: Ron Weasly, Age: 14}]

Explanation :
Here we have taken a list of students through list1 variable and a searching parameter through searchingStr variable. Then we use where() method where student represents all students one by one and the line student["Name"]!.contains(searchingStr) || student["Age"]!.contains(searchingStr) checks if “Name” and “Age” strings contains the string “Weasly” or not.