techworks

 How can we make dashed line in flutter? Dart does not have support for this yet. We need to make custom widget for showing dashed line. Code is given below. class LinePainter extends CustomPainter { @override void paint ( Canvas canvas, Size size) { var max = size. width ; debugPrint ( "LinePainter max= $ max " ); var dashWidth = 5.0 ; var dashSpace = 5.0 ; double startX = 0 ; final paint = Paint ().. color = Colors . grey ; while ( max >= 0 ) { canvas.drawLine( Offset ( startX , 0 ), Offset ( startX + dashWidth , 0 ),           paint .. strokeWidth = 1 ); final space = ( dashSpace + dashWidth ); startX += space ; max -= space .toInt(); } } @override bool shouldRepaint ( CustomPainter oldDelegate) { return false ; } } Above code will paint a line of width = size. width. To use this painter as widget, we have to use CustomPaint (painter: LinePainter (),size:Size(400,1)) It will ...

We have to encrypt our data while saving or sending over the Internet. We have to use shared key algorithms for encryption because they are fast. But what to do with the keys, how to generate and keep them safe? Developers usually use some of the approaches mentioned below: 1. Generate shared key in the app with shared logic in app and server. This can be used for encrypting/decrypting data locally and for sending data over Internet. Problem with this approach is, app can be decompiled and logic can reconstructed. Once the logic is reconstructed hacker can keep making the keys as and when required. 2. Get key from Server and use it. Security of the key depends on how the key is transported to Mobile app. If someone can grab it, then it is compromised and can be used to decrypt data and can even be used to modify it.  Recommended approach for this is to use HTTPS connection and send key on it. Ideally new key should be used with each request, as this gives very little time to the ha...

Have you tried to mock a method in Kotlin? As mentioned in this guide we can simply use following code to make it work. //You can mock concrete classes, not just interfaces  LinkedList mockedList = mock(LinkedList.class); / /stubbing  Mockito.when(mockedList.get(0)).thenReturn("first"); If you try it on kotlin class, it will fail with exception MissingMethodInvocationException. e.g. open class DummyPresenter { fun getSomeValue():String{ return "Some Value" } } @RunWith (MockitoJUnitRunner:: class ) class ExampleUnitTest { @Test fun testCallGetSomeValue() { val presenter: DummyPresenter = mock(DummyPresenter:: class . java ) `when`(presenter.getSomeValue()).thenReturn( "Some other value" ) val result = TestClass().callGetSomeValue(presenter) println ( "Test Result: $ result " ) assertEquals( "Some other value" ,result) } } org.mockito.exceptions.misusing.MissingMethodInvocationException:  when() requi...

We will use  device_info package for finding these details. Use this link to check latest version of the package.  Add  package_info : ^0.4.0+3 in pubspec.yaml file of your project. below  dependencies :    flutter :      sdk : flutter     package_info : ^0.4.0+3 Using next code sample you can retrieve the details. Future<List<String>> getDeviceDetails() async {     String deviceName;     String deviceVersion;     String identifier;     final DeviceInfoPlugin deviceInfoPlugin = DeviceInfoPlugin();     try {       if (Platform.isAndroid) {                  var build = await deviceInfoPlugin.androidInfo;         deviceName = build.model;         deviceVersion = build.version.toString();         identifier = build.androidId; //UUID for Android   ...

Coming from Android background https://flutter.dev/docs/get-started/flutter-for/android-devs https://codelabs.developers.google.com/codelabs/from-java-to-dart/#0 Coming from iOS background https://flutter.dev/docs/get-started/flutter-for/ios-devs Find out which widget to choose: https://flutter.dev/docs/development/ui/widgets/material https://flutter.dev/docs/development/ui/layout https://flutter.dev/docs/development/ui/widgets How to use Assets? https://flutter.dev/docs/development/ui/assets-and-images Create flavours? https://flutter.dev/docs/deployment/flavors Building widget based on api Response https://medium.com/nonstopio/flutter-future-builder-with-list-view-builder-d7212314e8c9 Building widget events of stream https://codingwithjoe.com/flutter-building-a-widget-with-streambuilder/

If you want to use context in view model, you can't use ViewModel as  it does not provide you context needed for creating Database. So Android architecture components introduced AndroidViewModel. If we use ViewModelProvider(this).get(ProductListingVM::class. java ), it will cause error "java.lang.Class<com.example.swapnil.sat.models.ProductListingVM> has no zero argument constructor" thrown at runtime. So, how to use it? We shall pass AndroidViewModelFactory instance while creating the ViewModelProvider.  Let's have a look. MainActivity.kt import androidx.appcompat.app.AppCompatActivity import androidx.lifecycle.ViewModelProvider class MainActivity : AppCompatActivity() { lateinit var viewModel : ProductListingVM override fun onCreate(savedInstanceState: Bundle?) { super .onCreate(savedInstanceState) setContentView(R.layout. activity_main ) viewModel =ViewModelProvider( this , ViewModelProvider.Andro...

Purpose of this post is to create layout like If you notice, label "New" should move along with email title, i.e. if email title is wide it should move up to left of date, if title is small then should stick with title. While moving to end, title should ellipsize. It is shown below. Here is how we can achieve it. Constraint right of  tvTitle  to  tvTime  text view. It should have right margin of 64dp. How I have reached 64dp? "New" label fits properly inside width of 56dp. Add 4dp margin on both sides of new label, it comes to 64 dp. 56 (width)+ 4 (left margin) + 4 (right margin) = 64 dp Now add  tvNew  with left constraint to  tvTitle  and 4dp left margin. To make  tvTitle  to have small width when text is small (e.g. "Email Subject"), add  app :layout_constraintWidth_default= "wrap"  in the layout. Complete layout looks like this.