我花了一点时间试图找出一种方法,将标题添加到RecyclerView
,但没有成功.
到目前为止,我得到的是:
@Override
protected void onCreate(Bundle savedInstanceState) {
...
layouManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layouManager);
LayoutInflater inflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
headerPlaceHolder = inflater.inflate(R.layout.view_header_holder_medium, null, false);
layouManager.addView(headerPlaceHolder, 0);
...
}
LayoutManager
似乎是处理RecyclerView
件物品的对象.由于找不到任何addHeaderView(View view)
方法,我决定使用LayoutManager
的addView(View view, int position)
方法,并在第一个位置添加标题视图,作为标题.
这就是事情变得更加丑陋的地方:
java.lang.NullPointerException: Attempt to read from field 'android.support.v7.widget.RecyclerView$ViewHolder android.support.v7.widget.RecyclerView$LayoutParams.mViewHolder' on a null object reference
at android.support.v7.widget.RecyclerView.getChildViewHolderInt(RecyclerView.java:2497)
at android.support.v7.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:4807)
at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:4803)
at com.mathieumaree.showz.fragments.CategoryFragment.setRecyclerView(CategoryFragment.java:231)
at com.mathieumaree.showz.fragments.CategoryFragment.access$200(CategoryFragment.java:47)
at com.mathieumaree.showz.fragments.CategoryFragment$2.success(CategoryFragment.java:201)
at com.mathieumaree.showz.fragments.CategoryFragment$2.success(CategoryFragment.java:196)
at retrofit.CallbackRunnable$1.run(CallbackRunnable.java:41)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
在让几个NullPointerExceptions
人在活动创建的不同时刻try 调用addView(View view)
之后(还try 在一切都设置好后添加视图,甚至包括Adapter的数据),我意识到我不知道这样做是否正确(看起来也不是).
PS:另外,一个除了LinearLayoutManager
之外还可以处理GridLayoutManager
的解决方案将非常感激!