Example Injection

demo.java

class A {
  a()
}

class B {
  b()
}

class C {
  
  A a;
  B b;
  
  setA( A a ) {
    this.a = a;
  }
  
  setB( B b ) {
    this.b = b;
  }
  
  main() {
    a.a();
    b.b();
  }
  
}