How to get Context when you call a method in a different class?

Lets have an basic understanding of Context.

Context allows access to application-specific resources and classes, as well as calls for application-level operations such as launching activities, broadcasting and receiving intents, etc.

A Context represents your environment. It represents the state surrounding where you are in your system.

An Android app has activities. Context is like a handle to the environment your application is currently running in. The activity object inherits the Context object.

So, how to access Context in your application ?

• getContext(): Returns the context within the currently active Activity. You can also use this for inflating layouts and menus, register context menus, instantiating widgets, start other activities, create new Intent within an Activity etc.

Example: View.getContext() returns the Context the view is currently running in. Usually the currently active Activity.

View mView = this.getLayoutInflater().inflate(R.layout.myLayout, myViewGroup);

Or,

Intent mIntent = new Intent(this, MyActivity.class);
this.startActivity(mIntent);

• getApplicationContext(): Returns the Context for the entire application, instead of the current Activity i.e. if you need a Context tied to the lifecycle of the entire application, not just the current Activity. This Context is widely used as it is safest to use as this Context exists for the lifespan of the application.

Example: Bind an application-wide class.

Intent mIntent = new Intent(this, MyPersistent.class);
MyServiceConnection mServiceConnection = new MyServiceConnection();
if (mServiceConnection != null) {
    getApplicationContext().bindService(mIntent, mServiceConnection, Context.BIND_AUTO_CREATE);
}

• getBaseContext(): Returns a Context from another context within application that you can access. This method has a limited usage.The method is relevant when you have a ContextWrapper.

ContextWrapper is, "Proxying implementation of Context that simply delegates all of its calls to another Context. Can be subclassed to modify behavior without changing the original Context." (as per javadocs)..

Now, a question might arise ! How would one access the Context object inside of a class that does not extend Activity ? So, it can be achieved by :

• Passing Context as an object to other class: For a class that does not have an access to any of the Context mentioned above. Context can be passed to such class through its constructor.

Example:

public class MyActivity extends Activity {
    private Context context;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);        
        context = getApplicationContext();
        new Helper(context);
    }
}

public class Helper {
    Context mContext;
    Helper(Context ctx){
        this.mContext= ctx;
    }
//Now you can use this mContext anywhere in your class.
}

And finally, to get Context anywhere in your application you can define a new class in your application :

public class MyContext extends Application {
    private static MyContext instance;

    @Override
    public void onCreate() {
        instance = this;
        super.onCreate();
    }

    public static Context getContext(){
        return instance;
        // or return instance.getApplicationContext();
    }
}

In your manifest you need to add this class to the "Name" field in the "Application" tab, like this:

<application
android:name="com.example.app.MyContext "
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
.......
<activity
......
</activity>

To get Context anywhere in your application, i.e. in any class of your project, you can call the function of this class, like this:

MyContext.getContext();

This function will return a Context that you can use to carry out your tasks.

So, coming to your question. I guess the last two methods can solve your problem i.e passing the Context object to the class and define a new class that extends Application.

That's all @Achmad Naufal Syafiq. This is my best effort to help you out.