package com.example.chenrui.app1;

import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.example.chenrui.common.Chat;

import java.util.List;

public class ChatAdapter extends RecyclerView.Adapter<ChatAdapter.ViewHolder> {

    private List<Chat> chatList;

    public ChatAdapter(List<Chat> chatList) {
        this.chatList = chatList;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.chat_item,viewGroup,false);
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull final ViewHolder viewHolder, final int i) {
        Chat chat = chatList.get(i);
        viewHolder.chatText.setText(chat.getContent());
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(viewHolder.chatText.getLayoutParams());
        if(chat.getTargetUser().equals("张三")) {
            params.gravity = Gravity.LEFT;
        } else {
            params.gravity = Gravity.RIGHT;
        }
        viewHolder.chatText.setLayoutParams(params);

        if(onItemClickListener!=null) {
            viewHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    onItemClickListener.onItemLongClick(viewHolder.itemView,i);
                    return false;
                }
            });
        }
    }

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

    static  class ViewHolder extends  RecyclerView.ViewHolder {

        TextView chatText;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);

            chatText = itemView.findViewById(R.id.chatText);
        }
    }

    private OnItemClickListener onItemClickListener;
    public interface OnItemClickListener{
        void onItemLongClick(View view , int pos);
    }

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        this.onItemClickListener = onItemClickListener;
    }
}

package com.example.chenrui.app1;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.PopupMenu;
import android.widget.Spinner;

import com.example.chenrui.common.Chat;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final RecyclerView chatList = findViewById(R.id.chatList);

        final List<Chat> chatData = new ArrayList<Chat>();
        final ChatAdapter chatAdapter = new ChatAdapter(chatData);
        chatList.setAdapter(chatAdapter);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        chatList.setLayoutManager(layoutManager);
        chatAdapter.setOnItemClickListener(new ChatAdapter.OnItemClickListener() {
            @Override
            public void onItemLongClick(View view, final int pos) {
                PopupMenu popupMenu = new PopupMenu(MainActivity.this,view);
                popupMenu.getMenuInflater().inflate(R.menu.menu3,popupMenu.getMenu());

                //弹出式菜单的菜单项点击事件
                popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {

                    @Override
                    public boolean onMenuItemClick(MenuItem item) {
                        if(item.getItemId()==R.id.delete) {
                            chatData.remove(pos);
                            chatAdapter.notifyItemRemoved(pos);
                        }
                        return false;
                    }
                });
                popupMenu.show();
            }
        });

        final Spinner targetUser = findViewById(R.id.targetUser);
        String[] data = {"张三","李四"};
        ArrayAdapter<String> adapter = new ArrayAdapter<String> (this,R.layout.support_simple_spinner_dropdown_item,data);
        targetUser.setAdapter(adapter);

        final EditText chatContent = findViewById(R.id.chatContent);

        Button chatSubmit = findViewById(R.id.chatSubmit);
        chatSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(!chatContent.getText().toString().equals("")) {
                    String user = targetUser.getSelectedItem().toString();
                    chatData.add(new Chat(user, chatContent.getText().toString()));

                    chatAdapter.notifyItemInserted(chatData.size() - 1);
                    chatList.scrollToPosition(chatData.size() - 1);
                    chatContent.setText("");
                }
            }
        });
    }
}