int android.support.v7.widget.RecyclerView$ViewHolder.mItemViewType' on a null.....

Android.support.v7.widget.RecyclerView$ViewHolder.mItemViewType' on a null..空指針問題，費勁心思才找到報空指針的原因：

代碼是這樣的，有多種布局類型

 

@Override
    public int getItemViewType(int position) {
        BmobIMMessage message = msgs.get(position);
        if(message.getMsgType().equals(BmobIMMessageType.IMAGE.getType())){
            return message.getFromId().equals(currentUid) ? TYPE_SEND_IMAGE: TYPE_RECEIVER_IMAGE;
        }else if(message.getMsgType().equals(BmobIMMessageType.LOCATION.getType())){
            return message.getFromId().equals(currentUid) ? TYPE_SEND_LOCATION: TYPE_RECEIVER_LOCATION;
        }else if(message.getMsgType().equals(BmobIMMessageType.VOICE.getType())){
            return message.getFromId().equals(currentUid) ? TYPE_SEND_VOICE: TYPE_RECEIVER_VOICE;
        }else if(message.getMsgType().equals(BmobIMMessageType.TEXT.getType())){
            return message.getFromId().equals(currentUid) ? TYPE_SEND_TXT: TYPE_RECEIVER_TXT;
        }else if(message.getMsgType().equals(BmobIMMessageType.VIDEO.getType())){
            return message.getFromId().equals(currentUid) ? TYPE_SEND_VIDEO: TYPE_RECEIVER_VIDEO;
        }else if(message.getMsgType().equals("agree")) {//顯示歡迎
            return TYPE_AGREE;
        }else{
//            return -1;
            return  TYPE_AGREE;
        }

然后這是

getItemCount()

@Override
public int getItemCount() {
    return msgs.size();

}

最后發現是因為itemCount與viewType不匹配導致的

例如：

recyclerview總共有6種類型，現在只寫了一種類型測試，其他的都沒有些，才導致報空，然后在getItemCount中return 1;  就ok了