inject a class in angular code example

Example 1: create class angular

// to create a model class, we first need to create a new file
//f.e person.ts

export class Person {
 constructor(
  public name: string,
   public lastName: string,
   public age:number
  
  ) {}
}

//now that we have the model class we can create arrays that contain Person class elements

.
.
public people: Person[];
constructor(){
 this.people = [
   new Person ('Carla','Smith', 20 ),
    new Person ('Carlos','Smith', 25 ),
    new Person ('Andrea','Johnson', 23 ),
   
   ];
}

Example 2: how to inject service in component angular 6

you can inject service in components constructor:
constructor(public anyService: Service){}

Example 3: angular injector.create example

using Angular Injector
Internal class in @angular/core, StaticInjector, ReflectiveInjector 
uses resolveAndCreate([ClassNames])
the resolve variable from above resolver.get(ClassName) will give the object.
All this is handled internally when we inform the angular with the providers