App crash when data count is less than columns count in GridDividerItemDecoration

[adammo1990]

App crash when data count is less than columns count (if I'm using GridDividerItemDecoration)
Below log:

08-22 06:45:15.364 5852-5852/pl.myapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: pl.myapp, PID: 5852
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.view.View.getLayoutParams()' on a null object reference
at com.dgreenhalgh.android.simpleitemdecoration.grid.GridDividerItemDecoration.drawHorizontalDividers(GridDividerItemDecoration.java:84)
at com.dgreenhalgh.android.simpleitemdecoration.grid.GridDividerItemDecoration.onDraw(GridDividerItemDecoration.java:43)
at android.support.v7.widget.RecyclerView.onDraw(RecyclerView.java:3658)
at android.view.View.draw(View.java:15231)
at android.support.v7.widget.RecyclerView.draw(RecyclerView.java:3593)
at android.view.View.updateDisplayListIfDirty(View.java:14167)
at android.view.View.getDisplayList(View.java:14189)
at android.view.View.draw(View.java:14959)
at android.view.ViewGroup.drawChild(ViewGroup.java:3405)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3198)
at android.view.View.updateDisplayListIfDirty(View.java:14162)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:3389)
at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:3368)
at android.view.View.updateDisplayListIfDirty(View.java:14127)
at android.view.View.getDisplayList(View.java:14189)
at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:273)
at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:279)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:318)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2530)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2352)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1982)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:550)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
at android.os.Handler.h

[dgreenhalgh]

Hey @adammo1990, I'm currently working on a 2.0 version of the library and the sample that will take care of this issue. Thanks for the heads up!

[siju2014]

This can be used as a temporary fix if needed
`

   private void drawHorizontalDividers(Canvas canvas, RecyclerView parent) {
           int childCount = parent.getChildCount();
           int rowCount = childCount / mNumColumns;
           int lastRowChildCount = childCount % mNumColumns;
           int newChildCount;
            **if (childCount < mNumColumns) {
                 newChildCount = childCount;
               } else {
                newChildCount = mNumColumns;
               }**
    for (int i = 1; i < **newChildCount**; i++) {..}`

[ysmintor]

I try to decode the math in this calculation. Finally, I found I solve the problem. Here, I add some check in drawHorizalDividers() and drawVerticalDividers().And it is better use those to methods in onDrawOver().
But there still need someone try to find why no the first column items still have some tiny left margin in my case.

You can find the gist file in :https://gist.github.com/ysmintor/b974a7e0ab155cc9d9d8818182626e05

[mobiRic]

Apologies I have duplicated this in #33

I submitted a PR for it in #36 before reading the comment about an upcoming v2