added layout, view models, adapter and fragment

app/src/main/java/org/mian/gitnex/viewmodels/FilesViewModel.java

@@ -0,0 +1,59 @@
+package org.mian.gitnex.viewmodels;
+
+import android.util.Log;
+import androidx.annotation.NonNull;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
+import org.mian.gitnex.clients.RetrofitClient;
+import org.mian.gitnex.models.Files;
+import java.util.List;
+import retrofit2.Call;
+import retrofit2.Callback;
+import retrofit2.Response;
+
+/**
+ * Author M M Arif
+ */
+
+public class FilesViewModel extends ViewModel {
+
+    private static MutableLiveData<List<Files>> filesList;
+
+    public LiveData<List<Files>> getFilesList(String instanceUrl, String token, String owner, String repo) {
+
+        filesList = new MutableLiveData<>();
+        loadFilesList(instanceUrl, token, owner, repo);
+
+        return filesList;
+    }
+
+    public static void loadFilesList(String instanceUrl, String token, String owner, String repo) {
+
+        Call<List<Files>> call = RetrofitClient
+                .getInstance(instanceUrl)
+                .getApiInterface()
+                .getFiles(token, owner, repo);
+
+        call.enqueue(new Callback<List<Files>>() {
+
+            @Override
+            public void onResponse(@NonNull Call<List<Files>> call, @NonNull Response<List<Files>> response) {
+
+                if (response.isSuccessful()) {
+                    filesList.postValue(response.body());
+                } else {
+                    Log.i("onResponse", String.valueOf(response.code()));
+                }
+
+            }
+
+            @Override
+            public void onFailure(@NonNull Call<List<Files>> call, Throwable t) {
+                Log.i("onFailure", t.toString());
+            }
+
+        });
+    }
+
+}