修复bug

app/src/main/java/com/test/easy/easycleanerjunk/helps/MediaStoreUtils.java

@@ -6,6 +6,7 @@ import android.media.MediaScannerConnection;
 import android.net.Uri;
 import android.os.Build;
 import android.provider.MediaStore;
+import android.text.TextUtils;
 import android.util.Log;
 
 import com.test.easy.easycleanerjunk.bean.FileBean;
@@ -83,6 +84,9 @@ public class MediaStoreUtils {
 
     private static String getFileExtension(String fileName) {
         String extension = "unknown";
+        if(TextUtils.isEmpty(fileName)){
+            return extension;
+        }
         int i = fileName.lastIndexOf('.');
         if (i > 0 && i < fileName.length() - 1) {
             int s = i + 1;