exercise complete

app/src/main/java/com/example/android/android_me/ui/MainActivity.java

@@ -18,12 +18,13 @@
 
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
+import android.widget.Toast;
 
 import com.example.android.android_me.R;
 
 // This activity is responsible for displaying the master list of all images
 // TODO (4) Implement the MasterListFragment callback, OnImageClickListener
-public class MainActivity extends AppCompatActivity {
+public class MainActivity extends AppCompatActivity implements MasterListFragment.OnImageClickListener {
 
 
     @Override
@@ -33,6 +34,12 @@ protected void onCreate(Bundle savedInstanceState) {
 
     }
 
+    @Override
+    public void onImageSelected(int position) {
+        //Create a toast that displays the position that was clicked
+        Toast.makeText(this, "Position clicked =" + position, Toast.LENGTH_SHORT).show();
+    }
+
     // TODO (5) Define the behavior for onImageSelected; create a Toast that displays the position clicked
 
 }

app/src/main/java/com/example/android/android_me/ui/MasterListFragment.java

@@ -16,11 +16,13 @@
 
 package com.example.android.android_me.ui;
 
+import android.content.Context;
 import android.os.Bundle;
 import android.support.v4.app.Fragment;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.AdapterView;
 import android.widget.GridView;
 
 import com.example.android.android_me.R;
@@ -35,13 +37,36 @@ public class MasterListFragment extends Fragment {
         // The callback is a method named onImageSelected(int position) that contains information about
         // which position on the grid of images a user has clicked
 
+
+    OnImageClickListener mCallback;
+
+    public interface OnImageClickListener{
+        void onImageSelected(int position);
+    }
+
     // TODO (2) Override onAttach to make sure that the container activity has implemented the callback
 
+    @Override
+    public void onAttach(Context context) {
+        super.onAttach(context);
+
+        try {
+            mCallback = (OnImageClickListener) context;
+        } catch (ClassCastException e) {
+            throw new ClassCastException(context.toString() + "must implement OnImageClickListener");
+        }
+    }
+
 
     // Mandatory empty constructor
     public MasterListFragment() {
+
     }
 
+
+
+
+
     // Inflates the GridView of all AndroidMe images
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
@@ -61,6 +86,14 @@ public View onCreateView(LayoutInflater inflater, ViewGroup container,
 
         // TODO (3) Set a click listener on the gridView and trigger the callback onImageSelected when an item is clicked
 
+        gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
+            @Override
+            public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
+                //Trigger tbe callback method and pass in the position that was clicked
+                mCallback.onImageSelected(position);
+            }
+        });
+
         // Return the root view
         return rootView;
     }