Android: can I put Global Variables in BroadCastReceiver?

Question

I have 2 classes that I want them interacting each other:

First is Receiver.java :

public class Receiver extends BroadcastReceiver{
    private int var = 0;

    public void onReceive(Context context, Intent intent) {
        //Bunch of codes here
        method();
        //use var to do something}

    private void method() {
        //do something}

    public void setVar(int i) {
         var= i; }
}

Then I have another class that I hope to use to change the variable in Receiver , MainActivity.java :

public class MainActivity extends AppCompatActivity {

    private Receiver receiver;

    protected void onCreate(Bundle savedInstanceState) {
        receiver.setVar; 
        //Bunches of other codes 
}

The Receiver class listen to SMS message and respond, it extends BroadcastReceiver .

The MainActivity class change setting in Receiver class.

Since the original code put all variables inside the onReceive() :

• Will I be able to change variable var in the Receiver class if I put it outside of the method?

• Can MainActivity access and change variable in the Receiver class?

• Does the method() within Receiver class work?

Answer 1

The answer below is valid only for a BroadcastReceiver that is to be instantiated and registered/unregistered programmatically within an Activity as OP asked .

The answer won't work for a BroadcastReceiver that is to be declared within AndroidManifest and instantiated by the system, because once onReceive() returns the receiver is considered to be no longer active and a new instance will be created next time.

---

Receiver is a regular Java object, so

Will I be able to change variable var in the Receiver class if I put it outside of onReceive() ?

Yes. var is a class member of Receiver class.

Can MainActivity access and change variable in the Receiver class?

Yes. MainActivity has the receiver reference to a Receiver class instance.

Does the method() within Receiver class work?

Yes. You'll be able to call it after the receiver initialization.