How to get the context in the main class constructor?

Question

I searched everywhere and I decided to write here. I'm trying to achieve a connection when my app starts. My problem is that I need to pass the context to the AsyncTask (or create ProgressDialog earlier in the constructor) - but I also need the context.

The most important thing: I can't move things from constructor to onCreate, cause it will make a new Client every time I open the app, go back etc.

The problem is here that when the constructor is fired, I don't have context yet.

Any ideas?

Already tried with this: StartConnectionTask(this); but this is the same thing.

Found this: http://briandolhansky.com/blog/2013/7/11/snippets-android-async-progress implemented it and still the same. Context is null.

public class MainActivity extends AppCompatActivity {
public Client client;
public Button loginButton;
public static String host = "192.168.1.2";
public static int tcp_port = 8888, udp_port = 8889;

@Override
protected void onCreate(Bundle savedInstanceState) {
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.menu_layout);
}

public MainActivity(){
    client = new Client();
    client.start();
    Network.register(client);
    StartConnectionTask s = new StartConnectionTask(MainActivity.this);
    s.execute();
}

public class StartConnectionTask extends AsyncTask<Void, Void, Boolean> {

    private ProgressDialog conDialog;

    public StartConnectionTask(MainActivity activity) {
        conDialog = new ProgressDialog(activity);
    }
    @Override
    protected void onPreExecute() {
        conDialog.setTitle("Connecting with a server...");
        conDialog.setMessage("Connecting with " + host);
        conDialog.show();
        conDialog.setCancelable(false);
    }

Answer 1

you need to shift your code from MainActivity() to at the end of onCreate .

In android conventionally onCreate is the method where your activity starts as per activity lifecycle. you can easily pass context from here by passing this

Answer 2

As asked by OP, here's how you can override your Application class

public class App extends Application {

    private static App mInstance;
    private Client mClient;

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

        // magic and stuff
        // put anything here and in anywhere in your app, activity
        // fragment, service, whatever you want
        // do App.getInstance().whatever()
        // like App.getInstance().getClient()

        mClient = new Client();
    }

    public static synchronized App getInstance() {
        return mInstance;
    }

    public static Client getClient() {
        return mClient;
    }

}

And specify this in AndroidManifest.xml

    <application
        android:name=".App"
        ... >

Answer 3

Activity extend context class . when a activity is start it flow her life cycle so activities constructor no need you put this constructor code into on create method.

Answer 4

Rahul Tiwari's answer will do. But in case, if you want to implement Application class to get the context throughout your aplication, try this.

public class App extends Application {

public static Context context;

@Override
public void onCreate() {
    // Do your stuff here
    context = getApplicationContext();
    super.onCreate();
}  ...

And add this to your manifest

 <application android:label="@string/app_name"
    android:name="com.your.package.App ">