Fixed artist image updating

app/src/main/java/com/kabouzeid/gramophone/util/ArtistSignatureUtil.java

@@ -0,0 +1,47 @@
+package com.kabouzeid.gramophone.util;
+
+import android.annotation.SuppressLint;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.support.annotation.NonNull;
+
+import com.bumptech.glide.signature.StringSignature;
+
+import hugo.weaving.DebugLog;
+
+/**
+ * @author Karim Abou Zeid (kabouzeid)
+ */
+public class ArtistSignatureUtil {
+    private static final String ARTIST_SIGNATURE_PREFS = "artist_signatures";
+
+    private static ArtistSignatureUtil sInstance;
+
+    private final SharedPreferences mPreferences;
+
+    private ArtistSignatureUtil(@NonNull final Context context) {
+        mPreferences = context.getSharedPreferences(ARTIST_SIGNATURE_PREFS, Context.MODE_PRIVATE);
+    }
+
+    public static ArtistSignatureUtil getInstance(@NonNull final Context context) {
+        if (sInstance == null) {
+            sInstance = new ArtistSignatureUtil(context.getApplicationContext());
+        }
+        return sInstance;
+    }
+
+    @DebugLog
+    @SuppressLint("CommitPrefEdits")
+    public void updateArtistSignature(String artistName) {
+        mPreferences.edit().putLong(artistName, System.currentTimeMillis()).commit();
+    }
+
+    @DebugLog
+    public long getArtistSignatureRaw(String artistName) {
+        return mPreferences.getLong(artistName, 0);
+    }
+
+    public StringSignature getArtistSignature(String artistName) {
+        return new StringSignature(String.valueOf(getArtistSignatureRaw(artistName)));
+    }
+}

app/src/main/java/com/kabouzeid/gramophone/util/PreferenceUtil.java

@@ -67,7 +67,7 @@ public final class PreferenceUtil {
 
     private final SharedPreferences mPreferences;
 
-    public PreferenceUtil(@NonNull final Context context) {
+    private PreferenceUtil(@NonNull final Context context) {
         mPreferences = PreferenceManager.getDefaultSharedPreferences(context);
     }