Where and how to connect to external API in my service class?

Question

In my service class I would like to connect to external API. Where and how should I do it?

1) Inject in constructor ExternalClass and assign to private property. Next in other property in constructor call connect.

public MyClass(ExternalApi externalApi) {
    this.externalApi = externalApi;
    this.ExternalApiConnect externalApiConnect = externalApi.connect;
}    

public void firstMethod() {
   externalApiConnect.first();
}

public void secondMethod() {
   externalApiConnect.second();
}

2) Outside constructor, so if I build dependencies in DI, then I don't call connection to external service.

private ExternalApiConnect externalApiConnect;

public MyClass(ExternalApi externalApi) {
    this.externalApi = externalApi;

}    

public void firstMethod() {
   if (externalApiConnect == null) {
        externalApiConnect = externalApi.getConnect();
   }
   externalApiConnect.first();
}

public void secondMethod() {
   if (externalApiConnect == null) {
        externalApiConnect = externalApi.getConnect();
   }
   externalApiConnect.second();
}

But now I have two repetitions and I have state in my service class. I don't think the state should be in service class?

How is the best way for this?

Edit:

3)

public MyClass(ExternalApi externalApi) {
    this.externalApi = externalApi;
}    

public void firstMethod() {
   externalApi.getConnect().first();
}

public void secondMethod() {
   externalApi.getConnect().second();
}

Answer 1

First of all, you have a smell in your code, you shouldn't ever access a property directly like this externalApi.connect in your ExternalApi class, change the visibility of your instance variable connect, from public to private and create a public getter function to access it.

Secondly, if you only need the object connect in your class, you don't have to pass ExternalApi, inject only ExternalApiConnect.

In case you need both, remove the externalApiConnect variable from your class, it is already apart of the externalApi state, why duplicate references to an object...