NullInjectorError: No provider for code example

Example 1: NullInjectorError: No provider for HttpClient!

@NgModule({
...
imports:[ HttpClientModule ]
...
})

Example 2: NullInjectorError: No provider for HttpClient!

import { HttpClientModule } from '@angular/common/http';

Example 3: NullInjectorError: No provider for HttpHandler!

import { HttpClientModule } from '@angular/common/http';

@NgModule({
 imports: [
   BrowserModule,
   HttpClientModule
 ],
 ...