Code optimization. Added comments. Few comment mistake fixes

app/src/main/java/eu/kanade/tachiyomi/data/cache/ChapterCache.java

@@ -32,7 +32,7 @@ public class ChapterCache {
     /** Name of cache directory. */
     private static final String PARAMETER_CACHE_DIRECTORY = "chapter_disk_cache";
 
-    /** Application version. */
+    /** Application cache version. */
     private static final int PARAMETER_APP_VERSION = 1;
 
     /** The number of values per cache entry. Must be positive. */
@@ -55,7 +55,6 @@ public class ChapterCache {
      * @param context application environment interface.
      */
     public ChapterCache(Context context) {
-        // Set context.
         this.context = context;
 
         // Initialize Json handler.

app/src/main/java/eu/kanade/tachiyomi/data/cache/CoverCache.java

@@ -20,33 +20,70 @@ import java.io.OutputStream;
 
 import eu.kanade.tachiyomi.util.DiskUtils;
 
+/**
+ * Class used to create cover cache
+ * Makes us of Glide which can avoid repeating requests and save the file.
+ * It is not necessary to load the images to the cache.
+ * Names of files are created with the md5 of the thumbnailURL
+ */
 public class CoverCache {
 
+    /** Name of cache directory. */
     private static final String PARAMETER_CACHE_DIRECTORY = "cover_disk_cache";
 
-    private Context context;
+    /** Interface to global information about an application environment. */
-    private File cacheDir;
+    private final Context context;
 
+    /** Cache class used for cache management. */
+    private final File cacheDir;
+
+    /**
+     * Constructor of CoverCache.
+     * @param context application environment interface.
+     */
     public CoverCache(Context context) {
         this.context = context;
+
+        // Get cache directory from parameter.
         cacheDir = new File(context.getCacheDir(), PARAMETER_CACHE_DIRECTORY);
+
+        // Create cache directory.
         createCacheDir();
     }
 
+    /**
+     * Check if cache dir exist if not create directory.
+     * @return true if cache dir exist or is created.
+     */
     private boolean createCacheDir() {
+        // TODO return value never used.
         return !cacheDir.exists() && cacheDir.mkdirs();
     }
 
+    /**
+     * Download the cover with Glide (it can avoid repeating requests) and save the file.
+     * TODO maybe remove?
+     * @param thumbnailUrl url of thumbnail.
+     * @param headers headers included in Glide request.
+     */
     public void save(String thumbnailUrl, LazyHeaders headers) {
         save(thumbnailUrl, headers, null);
     }
 
-    // Download the cover with Glide (it can avoid repeating requests) and save the file on this cache
+    /**
-    // Optionally, load the image in the given image view when the resource is ready, if not null
+     * Download the cover with Glide (it can avoid repeating requests) and save the file.
-    public void save(String thumbnailUrl, LazyHeaders headers, ImageView imageView) {
+     * @param thumbnailUrl url of thumbnail.
+     * @param headers  headers included in Glide request.
+     * @param imageView imageView where picture should be displayed.
+     */
+    private void save(String thumbnailUrl, LazyHeaders headers, ImageView imageView) {
+
+        // Check if url is empty.
         if (TextUtils.isEmpty(thumbnailUrl))
+            // Do not try and create the string. Instead... only try to realize the truth. There is no string.
             return;
 
+        // Download the cover with Glide and save the file.
         GlideUrl url = new GlideUrl(thumbnailUrl, headers);
         Glide.with(context)
                 .load(url)
@@ -54,7 +91,10 @@ public class CoverCache {
                     @Override
                     public void onResourceReady(File resource, GlideAnimation<? super File> anim) {
                         try {
+                            // Copy the cover from Glide's cache to local cache.
                             add(thumbnailUrl, resource);
+
+                            // Check if imageView isn't null and show picture in imageView.
                             if (imageView != null) {
                                 loadFromCache(imageView, resource);
                             }
@@ -65,18 +105,31 @@ public class CoverCache {
                 });
     }
 
-    // Copy the cover from Glide's cache to this cache
+
-    public void add(String thumbnailUrl, File source) throws IOException {
+    /**
+     * Copy the cover from Glide's cache to local cache.
+     * //TODO rename add => copyToLocalCache?
+     * @param thumbnailUrl url of thumbnail.
+     * @param source the cover image.
+     * @throws IOException TODO not returned atm?
+     */
+    private void add(String thumbnailUrl, File source) throws IOException {
+        // Create cache directory. TODO is this needed. Already called in constructor.
         createCacheDir();
+
+        // Create destination file.
         File dest = new File(cacheDir, DiskUtils.hashKeyForDisk(thumbnailUrl));
+
+        // Check if file already exists, if true delete it.
         if (dest.exists())
             dest.delete();
 
+        // Write thumbnail image to file.
         InputStream in = new FileInputStream(source);
         try {
             OutputStream out = new FileOutputStream(dest);
             try {
-                // Transfer bytes from in to out
+                // Transfer bytes from in to out.
                 byte[] buf = new byte[1024];
                 int len;
                 while ((len = in.read(buf)) > 0) {
@@ -90,22 +143,40 @@ public class CoverCache {
         }
     }
 
-    // Get the cover from cache
+    /**
-    public File get(String thumbnailUrl) {
+     * Returns the cover from cache.
+     * TODO rename get => getCoverFromCache
+     * @param thumbnailUrl the thumbnail url.
+     * @return cover image.
+     */
+    private File get(String thumbnailUrl) {
         return new File(cacheDir, DiskUtils.hashKeyForDisk(thumbnailUrl));
     }
 
-    // Delete the cover from cache
+    /**
+     * Delete the cover file from the cache.
+     * TODO rename delete => deleteCoverFromCache.
+     * @param thumbnailUrl the thumbnail url.
+     * @return status of deletion.
+     */
     public boolean delete(String thumbnailUrl) {
+        // Check if url is empty.
         if (TextUtils.isEmpty(thumbnailUrl))
             return false;
 
+        // Remove file.
         File file = new File(cacheDir, DiskUtils.hashKeyForDisk(thumbnailUrl));
         return file.exists() && file.delete();
     }
 
-    // Save and load the image from cache
+    /**
-    public void saveAndLoadFromCache(ImageView imageView, String thumbnailUrl, LazyHeaders headers) {
+     * Save or load the image from cache
+     * @param imageView imageView where picture should be displayed.
+     * @param thumbnailUrl the thumbnail url.
+     * @param headers headers included in Glide request.
+     */
+    public void saveOrLoadFromCache(ImageView imageView, String thumbnailUrl, LazyHeaders headers) {
+        // If file exist load it otherwise save it.
         File localCover = get(thumbnailUrl);
         if (localCover.exists()) {
             loadFromCache(imageView, localCover);
@@ -114,8 +185,15 @@ public class CoverCache {
         }
     }
 
-    // If the image is already in our cache, use it. If not, load it with glide
+    /**
+     * If the image is already in our cache, use it. If not, load it with glide.
+     * TODO not used atm.
+     * @param imageView imageView where picture should be displayed.
+     * @param thumbnailUrl url of thumbnail.
+     * @param headers headers included in Glide request.
+     */
     public void loadFromCacheOrNetwork(ImageView imageView, String thumbnailUrl, LazyHeaders headers) {
+        // If localCover exist load it  from cache otherwise load it from network.
         File localCover = get(thumbnailUrl);
         if (localCover.exists()) {
             loadFromCache(imageView, localCover);
@@ -124,8 +202,11 @@ public class CoverCache {
         }
     }
 
-    // Helper method to load the cover from the cache directory into the specified image view
+    /**
-    // The file must exist
+     *  Helper method to load the cover from the cache directory into the specified image view.
+     * @param imageView imageView where picture should be displayed.
+     * @param file file to load. Must exist!.
+     */
     private void loadFromCache(ImageView imageView, File file) {
         Glide.with(context)
                 .load(file)
@@ -134,8 +215,13 @@ public class CoverCache {
                 .into(imageView);
     }
 
-    // Helper method to load the cover from network into the specified image view.
+    /**
-    // It does NOT save the image in cache
+     * Helper method to load the cover from network into the specified image view.
+     * It does NOT save the image in cache!
+     * @param imageView imageView where picture should be displayed.
+     * @param thumbnailUrl url of thumbnail.
+     * @param headers headers included in Glide request.
+     */
     public void loadFromNetwork(ImageView imageView, String thumbnailUrl, LazyHeaders headers) {
         GlideUrl url = new GlideUrl(thumbnailUrl, headers);
         Glide.with(context)