Maps

1. Create a Student Object

In Dart, you can represent an object like a student using a Map with key-value pairs.

Example Code

Copyvoid main() {
  // Single Student Object as a Map
  Map<String, dynamic> student = {
    "id": 1,
    "name": "John Doe",
    "age": 20,
    "grade": "A"
  };

  print("Student Object: $student");
}

Output:

CopyStudent Object: {id: 1, name: John Doe, age: 20, grade: A}

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2. Manipulate the Map

A. Append a New Key-Value Pair

To add a new property to the Map, simply use the key and assign a value.

Copyvoid main() {
  Map<String, dynamic> student = {
    "id": 1,
    "name": "John Doe",
    "age": 20,
    "grade": "A"
  };

  // Add a new key-value pair
  student["email"] = "johndoe@example.com";
  print("After Adding Email: $student");
}

Output:

CopyAfter Adding Email: {id: 1, name: John Doe, age: 20, grade: A, email: johndoe@example.com}

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B. Remove a Specific Key

Use the .remove() method to delete a key-value pair by its key.

Copyvoid main() {
  Map<String, dynamic> student = {
    "id": 1,
    "name": "John Doe",
    "age": 20,
    "grade": "A"
  };

  // Remove the 'grade' key
  student.remove("grade");
  print("After Removing Grade: $student");
}

Output:

CopyAfter Removing Grade: {id: 1, name: John Doe, age: 20}

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C. Edit a Value

To update a value, access the key and assign it a new value.

Copyvoid main() {
  Map<String, dynamic> student = {
    "id": 1,
    "name": "John Doe",
    "age": 20,
    "grade": "A"
  };

  // Update the 'age' value
  student["age"] = 21;
  print("After Updating Age: $student");
}

Output:

CopyAfter Updating Age: {id: 1, name: John Doe, age: 21, grade: A}

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D. Find a Value by Key

To retrieve a value, use the key directly.

Copyvoid main() {
  Map<String, dynamic> student = {
    "id": 1,
    "name": "John Doe",
    "age": 20,
    "grade": "A"
  };

  // Find value by key
  print("Student Name: ${student['name']}");
  print("Student Age: ${student['age']}");
}

Output:

CopyStudent Name: John Doe
Student Age: 20

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3. Full Example

Here’s the full code combining all the operations:

Copyvoid main() {
  // Single Student Object
  Map<String, dynamic> student = {
    "id": 1,
    "name": "John Doe",
    "age": 20,
    "grade": "A"
  };

  print("Original Student Object: $student");

  // Append
  student["email"] = "johndoe@example.com";
  print("After Adding Email: $student");

  // Edit
  student["age"] = 21;
  print("After Updating Age: $student");

  // Find
  print("Student Name: ${student['name']}");
  print("Student Email: ${student['email']}");

  // Remove
  student.remove("grade");
  print("After Removing Grade: $student");
}

---

Output

CopyOriginal Student Object: {id: 1, name: John Doe, age: 20, grade: A}
After Adding Email: {id: 1, name: John Doe, age: 20, grade: A, email: johndoe@example.com}
After Updating Age: {id: 1, name: John Doe, age: 21, grade: A, email: johndoe@example.com}
Student Name: John Doe
Student Email: johndoe@example.com
After Removing Grade: {id: 1, name: John Doe, age: 21, email: johndoe@example.com}

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