RecyclerView再记录

怼烎@ 2022-05-10 08:40 150阅读 0赞

最近开发用到了关于RecyclerView的知识，觉得了解还不够深刻，再将demo记录一遍加深记忆。按照自己对RecyclerView流程的感受：在MainActivity中对RecyclerView组件进行声明，之后实例化一个LinerLayoutManager布局管理器，使用setLayoutManager对其进行处理，再实例化一个adapter适配器，用setAdapter进行处理。  
    首先，根据自己的业务需求创建entity实体类。包名略过

public class Msg {
        public static final int TYPE_RECEIVED = 0;
        public static final int TYPE_SEND = 1;
    
        private String content;
        private int type;
    
        public Msg(String content, int type) {
            this.content = content;
            this.type = type;
        }
    
        public String getContent() {
            return content;
        }
    
        public int getType() {
            return type;
        }
    
    }

之后，编写适合项目的适配器并使其继承RecyclerView.Adapter

public class MsgAdapter extends RecyclerView.Adapter<MsgAdapter.ViewHolder>{
        private List<Msg> mMsgList;
    
        static class ViewHolder extends RecyclerView.ViewHolder{
            LinearLayout leftLayout;
            LinearLayout rightLayout;
            TextView leftMsg;
            TextView rightMsg;
    
            public ViewHolder(View view){
                super(view);
                leftLayout = (LinearLayout) view.findViewById(R.id.left_layout);
                rightLayout = (LinearLayout) view.findViewById(R.id.right_layout);
                leftMsg = (TextView) view.findViewById(R.id.left_msg);
                rightMsg = (TextView) view.findViewById(R.id.right_msg);
            }
        }
    
        public MsgAdapter(List<Msg> msgList){
            mMsgList = msgList;
        }
    
        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int position) {
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.msg_item,parent,false);
            return new ViewHolder(view);
        }
    
        @Override
        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
            Msg msg = mMsgList.get(position);
    
            if (msg.getType() == Msg.TYPE_RECEIVED){
                holder.leftLayout.setVisibility(View.VISIBLE);
                holder.rightLayout.setVisibility(View.GONE);
                holder.leftMsg.setText(msg.getContent());
            } else if(msg.getType() == Msg.TYPE_SEND){
                holder.rightLayout.setVisibility(View.VISIBLE);
                holder.leftLayout.setVisibility(View.GONE);
                holder.rightMsg.setText(msg.getContent());
            }
        }
    
        @Override
        public int getItemCount() {
            return mMsgList.size();
        }
    }

因为项目涉及到线程相关的知识，所以将MainActivity中的代码置于线程池。

private void showInfo(final String text,final String answer) {
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    System.out.println("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!!!");
                    LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this);
                    msgRecyclerView.setLayoutManager(layoutManager);
                    adapter = new MsgAdapter(msgList);
                    msgRecyclerView.setAdapter(adapter);
                    Msg msg1 = new Msg(text, Msg.TYPE_RECEIVED);
                    msgList.add(msg1);
                    Msg msg2 = new Msg(answer, Msg.TYPE_SEND);
                    msgList.add(msg2);
                    //若有新的消息进入，定位并滚动至新消息位置
                    adapter.notifyItemInserted(msgList.size() - 1);
                    msgRecyclerView.scrollToPosition(msgList.size() - 1);
                }
            });
        }

这里存在一个未解决的问题：若在MainActivity中通过Intent启动别的活动，再返回主活动时会出现继续创建新线程的问题，此线程池内的代码会被二次调用，有待排查，抽空写这边博客的目的就是理清思路，在之后的故障排查中找到属于自己的感觉。