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("");

                }

            }

        });

    }

}