Get Activity (this) inside setOnClickListener

Question

I'm new in java and android development and I have one issue, let me explain. I have custom interface and custom class which use this as a listener.

In my HomeActivity I call method on my custom class and the class respond via listeners (interface), this is short version:

public class HomeActivity extends Activity implements WebClientResponseListener {
    private User user;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        //....
        // I call my class and add this as a listener:
        MyWebServiceClient mws = new MyWebServiceClient(getApplicationContext());
        mws.getProducts(this.user.getToken(), this)
    }
    //....
    @Override
    public void onDataDownloadSuccess(JSONObject jsonObject) {
        Log.d("DATA", "SUCCESS");
    }
}

When I run it like that everything works fine. The onDataDownloadSuccess method is called and I can see log output.

The issue appears when I try to run it from OnClickListener:

private void sendRequest() {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle(getString(R.string.request_info_title));
    builder.setItems(items, this);
    //.....
    builder.create().show();
}

Later in the same activity I have:

public void onClick(DialogInterface dialogInterface, int which) {
    MyWebServiceClient mws = new MyWebServiceClient(getApplicationContext());
     mws.getProducts(user.getToken(), this)
}

In this situation my listener onDataDownloadSuccess method is not called. I can see in in the console:

unregisterIRListener() is called

and

GC_FOR_ALLOC freed 1613K, 35% free 13400K/20408K, paused 18ms, total 18ms

I was looking for the solution on line and I've already tried some stuff for example:

//in OnClick
mws.getProducts(user.getToken(), HomeActivity.this);

I created private variable HomeActivity and in onCreate I call

homeActivity = this;

and later in onClick I was trying to pass homeActivity instead of this but with no luck. Thanks in advance.

Answer 1

always try to use YOUR_ACTIVITY_NAME.this because when you use only "this" , it point to the current context . let say you are in OnClickListener , it is an anonymous class so, when you use this inside this. it will point to the button not to the activity . Therefore, you need to point towards activity by using activityname.this.

Answer 2

As you need context and not activity , variable needs to be:

Context homeActivity;

or

Context context;  

Then in onCreate()

context=this; 

use that context or homeActivity in your activity or HomeActivity.this

Inside the click listener, " this " is a reference for the click listener.

Answer 3

您可以创建一个Context实例并将其在侦听器外部初始化为this ，然后只需在需要的地方调用它

Answer 4

The above solution should work perfectly fine but still adding some flavors in it. Thought it will be helpful for someone to understand better.

public class SampleActivity extends AppCompatActivity {

private Context sampleActivityContext; 
private Button continueButton;
// All your class level variables/fields declared in this section

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    sampleActivityContext = this; // Assigning the current activity(i.e.,) SampleActivity context
    .......
    continueButton = findViewById(R.id.continueButton); // Map the UI element from the XML to the corresponding java element
    .......  
   // Setting the onclick listener for the button 
    continueButton.setOnClickListener(new View.onClickListener() {
 @Override
  public void onClick(View view) {
 // When you need the context of the activity use sampleActivityContext 
 // instead of this keyword as this will refer the current view/button within the section 
// or you can prefer SampleActivity.this as well 

} 
}