用法一样，但是run的时候空指针异常

[zyxzhangyuxia]

java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.view.View.getLayoutParams()' on a null object reference
at com.example.library.AutoFlowLayout.setGridLayout(AutoFlowLayout.java:319)
at com.example.library.AutoFlowLayout.onLayout(AutoFlowLayout.java:303)
at android.view.View.layout(View.java:17529)
at android.view.ViewGroup.layout(ViewGroup.java:5612)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)