How to start Activity in adapter?

I have a ListActivity with my customized adapter and inside each of the view, it may have some buttons, in which I need to implement OnClickListener. I need to implement the OnClickListener in the adapter. However, I don't know how to call the function like startActivity() or setResult(). Since the adapter doesn't extend to Activity.

So what is the开发者_如何学C best way to solve this problem?

Thanks.

Just pass in the current Context to the Adapter constructor and store it as a field. Then inside the onClick you can use that context to call startActivity().

pseudo-code

public class MyAdapter extends Adapter {
     private Context context;

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

     public View getView(...){
         View v;
         v.setOnClickListener(new OnClickListener() {
             void onClick() {
                 context.startActivity(...);
             }
         });
     }
}

When implementing the onClickListener, you can use v.getContext.startActivity.

btn.setOnClickListener(new OnClickListener() {                  
    @Override
    public void onClick(View v) {
        v.getContext().startActivity(PUT_YOUR_INTENT_HERE);
    }
});

public class MyAdapter extends Adapter {
     private Context context;      


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


     public View getView(...){  
         View v;  
         v.setOnClickListener(new OnClickListener() {
             void onClick() {
                  Intent intent= new Intent(context, ToActivity.class); 
                   intent.putExtra("your_extra","your_class_value");
                 context.startActivity(intent);
             }
         });
     }
}

For newer versions of sdk you have to set flag activity task.

public void onClick(View v)
 {
     Intent myactivity = new Intent(context.getApplicationContext(), OtherActivity.class);
     myactivity.addFlags(FLAG_ACTIVITY_NEW_TASK);
     context.getApplicationContext().startActivity(myactivity);
 }

Simple way to start activity in Adopter's button onClickListener:

Intent myIntent = new Intent(view.getContext(),Event_Member_list.class);                    myIntent.putExtra("intVariableName", eventsList.get(position).getEvent_id());
                view.getContext().startActivity(myIntent);

callback from adapter to activity can be done using registering listener in form of interface: Make an interface:

      public MyInterface{
         public void  yourmethod(//incase needs parameters );
         }

In Adapter Let's Say MyAdapter:

    public MyAdapter extends BaseAdapter{
       private MyInterface listener;

    MyAdapter(Context context){
        try {
            this. listener = (( MyInterface ) context);
              } catch (ClassCastException e) {
               throw new ClassCastException("Activity must implement MyInterface");
          }

//do this where u need to fire listener l

          try {
                listener . yourmethod ();
            } catch (ClassCastException exception) {
               // do something
            }

      In Activity Implement your method:


         MyActivity extends AppCompatActivity implements MyInterface{

                yourmethod(){
                //do whatever you want
                     }
                     }

view.getContext().startActivity(intent);

view - public void onClick(View view) OnClick of image.

First Solution:

You can call start activity inside your adapter like this:

public class YourAdapter extends Adapter {
     private Context context;

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

     public View getView(...){
         View v;
         v.setOnClickListener(new OnClickListener() {
             void onClick() {
                 context.startActivity(...);
             }
         });
     }
}

Second Solution:

You can call onClickListener of your button out of the YourAdapter class. Follow these steps:

Craete an interface like this:

public YourInterface{
         public void  yourMethod(args...);
}

Then inside your adapter:

    public YourAdapter extends BaseAdapter{
               private YourInterface listener;

           public YourAdapter (Context context, YourInterface listener){
                    this.listener = listener;
                    this.context = context;
           }

           public View getView(...){
                View v;
         v.setOnClickListener(new OnClickListener() {
             void onClick() {
                 listener.yourMethod(args);
             }
         });
}

And where you initiate yourAdapter will be like this:

YourAdapter adapter = new YourAdapter(getContext(), (args) -> {
            startActivity(...);
        });

This link can be useful for you.

If you want to redirect on url instead of activity from your adapter class then pass context of with startactivity.

btnInstall.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent=new Intent(Intent.ACTION_VIEW, Uri.parse(link));
                intent.setData(Uri.parse(link));
                context.startActivity(intent);
            }
        });