README

Author: Daniel Novak

README.md

@@ -0,0 +1,45 @@
+UpdatableFragmentStatePagerAdapter
+================
+
+This is an improved version of the original [FragmentStatePagerAdapter](https://developer.android.com/reference/android/support/v4/app/FragmentStatePagerAdapter.html) with important changes that add support for changing the order and count of items.
+
+Two major problems exist in the FragmentStatePagerAdapter which make it impossible to use with ```notifyDataSetChanged()```, these are desribed as part of our article [Adventures with FragmentStatePagerAdapter](Adventures with FragmentStatePagerAdapter):
+
+- State bundles are assigned to wrong Fragments after the dataset order has changed
+http://speakman.net.nz/blog/2014/02/20/a-bug-in-and-a-fix-for-the-way-fragmentstatepageradapter-handles-fragment-restoration/
+- Crash in case the order of items is changed
+http://billynyh.github.io/blog/2014/03/02/fragment-state-pager-adapter/
+
+You can build and look at the [sample implementation](sample/src/main/java/eu/inloop/pager/sample/MainActivity.java).
+
+How to use
+--------
+
+The implemenation is the same as with the original FragmentStatePagerAdapter. 
+You need to override two methods in order to support dataset changes:
+
+```java
+@Override
+public int getItemPosition(Object object) {
+    YourFragment fragment = (YourFragment) object;
+    // ... determine the position of the fragment in your dataset 
+    // ... e.g. extract some ID from Arguments and search in your dataset
+}
+```
+You need to return POSITION_NONE in case the dataset doesn't contain the item anymore.
+Always returning POSITION_NONE will work but will have an impact on performance (current Fragments are recreated even if the position hasn't changed). 
+
+Also you need to return a unique identifier for an item based on the position. This isually means returning an "ID" or hashcode of the item.
+```java
+@Override
+public long getItemId(int position) {
+    // get the item in your dataset on this position and return some ID or hash code.
+}
+```
+
+Download
+--------
+
+```groovy
+compile 'eu.inloop:pageradapter:0.1.0'
+```

library/src/main/java/eu/inloop/pager/UpdatableFragmentPagerAdapter.java

@@ -181,7 +181,7 @@ public Parcelable saveState() {
     }
 
     @Override
-    public void restoreState(Parcelable state, ClassLoader loader) {
+    public void restoreState(@Nullable Parcelable state, ClassLoader loader) {
         if (state != null) {
             Bundle bundle = (Bundle) state;
             bundle.setClassLoader(loader);