Can not show Toast in OnItemClickListener inside Fragment

问题

I am trying to create a ListView in a Fragment. The listView appear correctly but when I complied the code shows error.

    import android.app.Fragment;
    import android.content.Context;
    import android.os.Bundle;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.AdapterView;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;
    import android.widget.Toast;

    public class ServiceFragment extends Fragment {
        private ListView serviceList;
        private String[] serviceString;
        public ServiceFragment(){}


        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
         Bundle savedInstanceState) {
         View rootView = inflater.inflate(R.layout.fragment_service, container, false);

           //build the list service
            serviceList = (ListView) rootView.findViewById(R.id.ServiceList);
            serviceString = getResources().getStringArray(R.array.service_list);

            ArrayAdapter<String> objAdapter = new ArrayAdapter<String>(this.getActivity(), android.R.layout.simple_list_item_1,serviceString );
            serviceList.setAdapter(objAdapter);

           //on click item Listener
           serviceList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
             @Override
             public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                String  itemValue    = (String) serviceList.getItemAtPosition(position);
                int itemPosition     = position;

                Toast.makeText(ServiceFragment.this,"Position :"+itemPosition+"  ListItem : " +itemValue , Toast.LENGTH_LONG).show();

             }
          });

         return rootView;
        }//end of onCreateView

}//end of class ServiceFragment

What's wrong with my code? Why doesn't Toast show up?

is it possible on click item start a detail activity where I can describe the meaning of item

Suppose List Item = Apple ,Mango, Banana onClick Item Details view = Apple is a brand or fruit, Banana is a fruit,Mango is a good fruit,

回答1:

What Wrong with my code ? Why the Toast does not show

Since you are on a Fragment you must use getActivity() instead of yourClass.this.

Change your Toast to this :

Toast.makeText(getActivity(),"Position :"+itemPosition+" ListItem : " +itemValue , Toast.LENGTH_LONG).show();

EDIT

For a detail Activity you must create an Activity first let's call it DetailActivity then you have to change your onItemClickListener() to this :

 serviceList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
         @Override
         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String  itemValue    = (String) serviceList.getItemAtPosition(position);
            int itemPosition     = position;

            Toast.makeText(getActivity(),"Position :"+itemPosition+"  ListItem : " +itemValue , Toast.LENGTH_LONG).show();

          Intent intent = new Intent(getActivity(), DetailActivity.class);
          intent.putExtra("DetailProductClicked", itemValue);
          startActivity(intent);

         }
      });

So in your DetailActivity.class you have to put this on your onCreate()

String nameFruit = intent.getStringExtra("DetailProductClicked");

Then depends what you have on this Activity you can do something like :

if (nameFruit.equals("Apple"){
   tv.setText(nameFruit +" is a brand or fruit");
}
if (nameFruit.equals("Mango"){
   tv.setText(nameFruit +" is a good fruit");
}
if (nameFruit.equals("Banana"){
   tv.setText(nameFruit +" is a fruit");
}

回答2:

To follow up @Skizo 's answer change your onItemClick to

  serviceList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
         @Override
         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String  itemValue    = (String) serviceList.getItemAtPosition(position);
            int itemPosition     = position;

            Intent nextIntent = new Intent(getActivity(), MyNextActivity.class); 
             // ... create a bundle to pass of the Object in your data at itemPosition
            startActivity(nextIntent);

         }
      });

realistically though i would use an interface in the Fragment like so and tell my Activity to start the new Activity rather than the fragment:

    import android.app.Fragment;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class ServiceFragment extends Fragment {
    private ListView serviceList;
    private String[] serviceString;
    private ItemListener mCallback;
    public ServiceFragment(){}


    public interface ItemListener{
         // use position or Object data here
         void onItemClicked(int position);
    }

    @Override
    public void onAttach(Activity activity){
        super.onAttach(activity);

        mCallback = (ItemListener) activity;
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
     Bundle savedInstanceState) {
     View rootView = inflater.inflate(R.layout.fragment_service, container, false);

       //build the list service
        serviceList = (ListView) rootView.findViewById(R.id.ServiceList);
        serviceString = getResources().getStringArray(R.array.service_list);

        ArrayAdapter<String> objAdapter = new ArrayAdapter<String>(this.getActivity(), android.R.layout.simple_list_item_1,serviceString );
        serviceList.setAdapter(objAdapter);

       //on click item Listener
       serviceList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
         @Override
         public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            String  itemValue    = (String) serviceList.getItemAtPosition(position);
            int itemPosition     = position;

            mCallback.onItemClicked(itemPosition);

         }
      });

     return rootView;
    }//end of onCreateView

}//end of class ServiceFragment

and then add implements ServiceFragment.ItemListener in your Activity:

 @Override
 public void onItemClicked(int position){
     // Now handling this element via the Activity, much cleaner
     Intent nextIntent = new Intent(this, MyNextActivity.class); 
             // ... create a bundle to pass of the Object in your data at itemPosition
            startActivity(nextIntent);

 }

来源：https://stackoverflow.com/questions/32596957/can-not-show-toast-in-onitemclicklistener-inside-fragment