make use of Butterknife

app/src/main/java/com/simplemobiletools/gallery/activities/MainActivity.java

@@ -40,12 +40,16 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import butterknife.BindView;
+import butterknife.ButterKnife;
+
 public class MainActivity extends AppCompatActivity
         implements AdapterView.OnItemClickListener, GridView.MultiChoiceModeListener, GridView.OnTouchListener,
         MediaScannerConnection.OnScanCompletedListener {
+    @BindView(R.id.directories_grid) GridView gridView;
+
     private static final int STORAGE_PERMISSION = 1;
     private List<Directory> dirs;
-    private GridView gridView;
     private int selectedItemsCnt;
     private Snackbar snackbar;
     private boolean isSnackbarShown;
@@ -56,6 +60,7 @@ public class MainActivity extends AppCompatActivity
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
+        ButterKnife.bind(this);
     }
 
     @Override
@@ -115,7 +120,6 @@ public class MainActivity extends AppCompatActivity
         dirs = new ArrayList<>(getDirectories().values());
         final DirectoryAdapter adapter = new DirectoryAdapter(this, dirs);
 
-        gridView = (GridView) findViewById(R.id.directories_grid);
         gridView.setAdapter(adapter);
         gridView.setOnItemClickListener(this);
         gridView.setMultiChoiceModeListener(this);

app/src/main/java/com/simplemobiletools/gallery/activities/PhotosActivity.java

@@ -37,13 +37,17 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.regex.Pattern;
 
+import butterknife.BindView;
+import butterknife.ButterKnife;
+
 public class PhotosActivity extends AppCompatActivity
         implements AdapterView.OnItemClickListener, GridView.MultiChoiceModeListener, MediaScannerConnection.OnScanCompletedListener,
         GridView.OnTouchListener {
+    @BindView(R.id.photos_grid) GridView gridView;
+
     private static final int STORAGE_PERMISSION = 1;
     private List<String> photos;
     private int selectedItemsCnt;
-    private GridView gridView;
     private String path;
     private Snackbar snackbar;
     private boolean isSnackbarShown;
@@ -54,6 +58,7 @@ public class PhotosActivity extends AppCompatActivity
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_photos);
+        ButterKnife.bind(this);
     }
 
     @Override
@@ -101,7 +106,6 @@ public class PhotosActivity extends AppCompatActivity
             return;
 
         final PhotosAdapter adapter = new PhotosAdapter(this, photos);
-        gridView = (GridView) findViewById(R.id.photos_grid);
         gridView.setAdapter(adapter);
         gridView.setOnItemClickListener(this);
         gridView.setMultiChoiceModeListener(this);

app/src/main/java/com/simplemobiletools/gallery/activities/ViewPagerActivity.java

@@ -31,24 +31,30 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.regex.Pattern;
 
+import butterknife.BindView;
+import butterknife.ButterKnife;
+import butterknife.OnClick;
+
 public class ViewPagerActivity extends AppCompatActivity
         implements ViewPager.OnPageChangeListener, View.OnSystemUiVisibilityChangeListener, MediaScannerConnection.OnScanCompletedListener,
         ViewPager.OnTouchListener {
+    @BindView(R.id.undo_delete) View undoBtn;
+    @BindView(R.id.view_pager) MyViewPager pager;
+
     private int pos;
     private boolean isFullScreen;
     private ActionBar actionbar;
     private List<String> photos;
-    private MyViewPager pager;
     private String path;
     private String directory;
     private boolean isUndoShown;
     private String toBeDeleted;
-    private View undoBtn;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_photo);
+        ButterKnife.bind(this);
 
         pos = 0;
         isFullScreen = true;
@@ -58,11 +64,8 @@ public class ViewPagerActivity extends AppCompatActivity
 
         path = getIntent().getStringExtra(Constants.PHOTO);
         MediaScannerConnection.scanFile(this, new String[]{path}, null, null);
-        undoBtn = findViewById(R.id.undo_delete);
-        undoBtn.setOnClickListener(undoDeletion);
         addUndoMargin();
         directory = new File(path).getParent();
-        pager = (MyViewPager) findViewById(R.id.view_pager);
         photos = getPhotos();
         if (isDirEmpty())
             return;
@@ -78,6 +81,14 @@ public class ViewPagerActivity extends AppCompatActivity
         updateActionbarTitle();
     }
 
+    @OnClick(R.id.undo_delete)
+    public void undoDeletion() {
+        isUndoShown = false;
+        toBeDeleted = "";
+        undoBtn.setVisibility(View.GONE);
+        reloadViewPager();
+    }
+
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         getMenuInflater().inflate(R.menu.viewpager_menu, menu);
@@ -141,16 +152,6 @@ public class ViewPagerActivity extends AppCompatActivity
         undoBtn.setVisibility(View.GONE);
     }
 
-    private View.OnClickListener undoDeletion = new View.OnClickListener() {
-        @Override
-        public void onClick(View v) {
-            isUndoShown = false;
-            toBeDeleted = "";
-            undoBtn.setVisibility(View.GONE);
-            reloadViewPager();
-        }
-    };
-
     private boolean isDirEmpty() {
         if (photos.size() <= 0) {
             deleteDirectoryIfEmpty();

app/src/main/java/com/simplemobiletools/gallery/adapters/DirectoryAdapter.java

@@ -14,6 +14,9 @@ import com.simplemobiletools.gallery.R;
 
 import java.util.List;
 
+import butterknife.BindView;
+import butterknife.ButterKnife;
+
 public class DirectoryAdapter extends BaseAdapter {
     private final Context context;
     private final List<Directory> dirs;
@@ -66,14 +69,12 @@ public class DirectoryAdapter extends BaseAdapter {
     }
 
     static class ViewHolder {
-        TextView dirName;
+        @BindView(R.id.dir_name) TextView dirName;
-        TextView photoCnt;
+        @BindView(R.id.photo_cnt) TextView photoCnt;
-        ImageView dirThumbnail;
+        @BindView(R.id.dir_thumbnail) ImageView dirThumbnail;
 
         public ViewHolder(View view) {
-            dirName = (TextView) view.findViewById(R.id.dir_name);
+            ButterKnife.bind(this, view);
-            photoCnt = (TextView) view.findViewById(R.id.photo_cnt);
-            dirThumbnail = (ImageView) view.findViewById(R.id.dir_thumbnail);
         }
     }
 }