How to use Context in android?

Question

WifiManager wifimanager = (WifiManager) context.getApplicationContext().getSystemService(Context.WIFI_SERVICE);

Why the context was used here?

Can any one explain?

Answer 1

According to official docs

Context is the global information about an application environment. This is an abstract class whose implementation is provided by the Android system. It allows access to application-specific resources and classes, as well as up-calls for application-level operations such as launching activities, broadcasting and receiving intents, etc.

If you want to use the WIFI_SERVICE which is a application-specific resource you have to use the context to retrieve the resource.

If you are inside activities or fragments, then you can call getApplicationContext().getSystemService(Context.WIFI_SERVICE) directly without using the context object because activities and fragments inherits from Context class.

But if you are in a non Activity or Fragment class then you have to pass the context object from the activity or fragment (with constructors or setters) to that class in order to get application specific resources.

An example

public class AnyClass{

    private Context context;

    public AnyClass(Context context){
        this.context = context;
    }

    ...

    WifiManager wifimanager = (WifiManager) context.getApplicationContext().getSystemService(Context.WIFI_SERVICE);
}