Location and GPS in Flutter - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Flutter package that provides location services.

Flutter

import '[1]';

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Apackage:flutter/widgets.dart

Bpackage:flutter/material.dart

Cpackage:location/location.dart

Dpackage:flutter/services.dart

Attempts:

3 left

💡 Hint

Common Mistakes

Importing material.dart instead of location.dart

Using widgets.dart which does not provide location features

The location package is used to access GPS and location services in Flutter apps.

2fill in blank

medium

Complete the code to create a Location instance to access GPS data.

Flutter

final location = [1]();

Drag options to blanks, or click blank then click option'

ALocationManager

BLocation

CGeoLocator

DGPSService

Attempts:

3 left

💡 Hint

Common Mistakes

Using classes not defined in the location package

Trying to instantiate a service class that does not exist

The Location class from the location package is used to get GPS data.

3fill in blank

hard

Fix the error in the code to request permission to access location.

Flutter

bool _serviceEnabled = await location.[1]();

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ArequestLocationPermission

BrequestPermission

CcheckPermission

DrequestService

Attempts:

3 left

💡 Hint

Common Mistakes

Using requestPermission() which asks for permission but not service status

Using checkPermission() which only checks permission status

The method requestService() asks the user to enable the location service if it is off.

4fill in blank

hard

Fill both blanks to get the current location coordinates asynchronously.

Flutter

LocationData currentLocation = await location.[1]();
double latitude = currentLocation.[2];

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AgetLocation

Blatitude

CgetCurrentPosition

Dlongitude

Attempts:

3 left

💡 Hint

Common Mistakes

Using getCurrentPosition() which is from a different package

Accessing longitude instead of latitude for latitude value

getLocation() fetches the current location data, and latitude accesses the latitude value.

5fill in blank

hard

Fill all three blanks to listen for location changes and update UI accordingly.

Flutter

location.[1].listen((LocationData currentLocation) {
  setState(() {
    _latitude = currentLocation.[2];
    _longitude = currentLocation.[3];
  });
});

Drag options to blanks, or click blank then click option'

AonLocationChanged

Blatitude

Clongitude

DgetLocation

Attempts:

3 left

💡 Hint

Common Mistakes

Using getLocation instead of onLocationChanged for continuous updates

Mixing up latitude and longitude properties

onLocationChanged is a stream that emits location updates. Inside the listener, latitude and longitude are accessed to update the UI.

Practice

1.

What is the main purpose of using the location feature in a Flutter app?

easy

A. To send text messages automatically

B. To change the device's screen brightness

C. To play music in the background

D. To find the device's current position on the map

Solution

1. Step 1: Understand location feature usage

   The location feature is used to get the device's position on Earth.

2. Step 2: Compare options with location purpose

   Only To find the device's current position on the map relates to finding the device's position, others are unrelated.

3. Final Answer:

   To find the device's current position on the map -> Option D

4. Quick Check:

   Location feature = Find position [OK]

Hint: Location means device position, not unrelated tasks [OK]

Common Mistakes:

• Confusing location with other device features
• Thinking location controls device settings
• Assuming location sends messages or plays music

2.

Which of the following is the correct way to request location permission in Flutter using the permission_handler package?

final status = await Permission.location.____();

easy

A. ask

B. request

C. get

D. allow

Solution

1. Step 1: Recall permission_handler syntax

   The package uses request() to ask for permission.

2. Step 2: Match method to code snippet

   Only request fits the method call to request permission.

3. Final Answer:

   request -> Option B

4. Quick Check:

   Permission request method = request() [OK]

Hint: Permission requests use request(), not ask or get [OK]

Common Mistakes:

• Using ask() instead of request()
• Confusing get() with permission request
• Using allow() which is not a method

3.

What will the following Flutter code print if the device's location is successfully fetched?

var location = await Geolocator.getCurrentPosition();
print('Lat: ${location.latitude}, Lon: ${location.longitude}');

medium

A. Lat: [some number], Lon: [some number]

B. Lat: 0.0, Lon: 0.0

C. SyntaxError

D. Lat: null, Lon: null

Solution

1. Step 1: Understand getCurrentPosition()

   This method returns the device's current latitude and longitude as numbers.

2. Step 2: Analyze print output

   The print statement outputs the latitude and longitude values, which are numbers, not null or zero by default.

3. Final Answer:

   Lat: [some number], Lon: [some number] -> Option A

4. Quick Check:

   getCurrentPosition() returns coordinates [OK]

Hint: getCurrentPosition() returns actual coordinates, not null [OK]

Common Mistakes:

• Assuming coordinates are zero or null by default
• Expecting syntax error from correct code
• Confusing method with one that returns null

4.

Identify the error in this Flutter code snippet that tries to get location updates:

StreamSubscription positionStream = Geolocator.getPositionStream().listen((Position position) {
  print(position.latitude);
});

positionStream.cancel();

medium

A. Missing permission check before listening to location stream

B. Using listen instead of subscribe

C. Calling cancel() immediately stops the stream

D. Position type should be String, not Position

Solution

1. Step 1: Check permission handling

   The code does not check or request location permission before starting the stream.

2. Step 2: Review other options

   Using listen is correct; cancel() is valid but should be called later; Position type is correct.

3. Final Answer:

   Missing permission check before listening to location stream -> Option A

4. Quick Check:

   Permission check required before location stream [OK]

Hint: Always check permission before accessing location stream [OK]

Common Mistakes:

• Skipping permission request before location access
• Confusing listen() with subscribe()
• Calling cancel() too early without reason
• Wrong type for position parameter

5.

You want your Flutter app to continuously track the user's location but only update the UI when the user moves more than 50 meters. Which approach is best?

hard

A. Use getCurrentPosition() repeatedly every second

B. Use getPositionStream() without filters and update UI every time

C. Use getPositionStream(distanceFilter: 50) to listen for updates

D. Use getLastKnownPosition() to get location once

Solution

1. Step 1: Understand continuous tracking with filtering

   The getPositionStream() method can listen for location changes and supports a distanceFilter to limit updates.

2. Step 2: Compare options for efficiency

   Use getPositionStream(distanceFilter: 50) to listen for updates uses distanceFilter: 50 to update only when user moves 50 meters, saving resources and avoiding UI overload.

3. Step 3: Eliminate other options

   Use getCurrentPosition() repeatedly every second is inefficient; C updates too often; D only gets location once.

4. Final Answer:

   Use getPositionStream(distanceFilter: 50) to listen for updates -> Option C

5. Quick Check:

   Use stream with distanceFilter for efficient updates [OK]

Hint: Use distanceFilter in stream to limit location updates [OK]

Common Mistakes:

• Polling location repeatedly instead of streaming
• Updating UI on every small location change
• Using getLastKnownPosition for continuous tracking