RecyclerView实现多种Item，最优雅的方式，getItemViewType（以即时通讯app为例子）

实现多种item有许多种方式，我们这里就用RecyclerView提供给我们的方式，getItemViewType。

这个方法是RecyclerView专门开放给我们用来实现多item类型的方法，所以他是最优雅的。

我仔细看过源码，这种方式用来实现多种Item，绝对是丝毫不影响性能的，请放心使用。

以即时通讯app为例子，你肯定要有一左一右的对话框吧。

所以在Adapter中先定义这两种ViewHolder。

private static class MeViewHolder extends RecyclerView.ViewHolder {
TextView mTvMyMsg;
ImageView mIvMyAvatar;

public MeViewHolder(View view) {
super(view);
mTvMyMsg = (TextView) view.findViewById(R.id.tv_my_msg);
mIvMyAvatar = (ImageView) view.findViewById(R.id.iv_my_avatar);
}
}

private static class FriendViewHolder extends RecyclerView.ViewHolder {
TextView mTvFriendMsg;
ImageView mIvFriendAvatar;

public FriendViewHolder(View view) {
super(view);
mTvFriendMsg = (TextView) view.findViewById(R.id.tv_friend_msg);
mIvFriendAvatar = (ImageView) view.findViewById(R.id.iv_friend_avatar);
}
}

getItemViewType方法，我这里list装的是bean，每个bean里都有一个，0代表我自己的对话，1代表对方的对话。

@Override
public int getItemViewType(int position) {
return list.get(position).getMsgType();
}

onCreateViewHolder方法，一目了然

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (context == null) {
context = parent.getContext();
}
if (viewType == TYPE_ME) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_rv_chat_me, parent, false);
return new MeViewHolder(view);
} else {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_rv_chat_friend, parent, false);
return new FriendViewHolder(view);
}
}

onBindViewHolder方法，也很简单

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof MeViewHolder) {
((MeViewHolder) holder).mTvMyMsg.setText(list.get(position).getMsgContent());
} else {
((FriendViewHolder) holder).mTvFriendMsg.setText(list.get(position).getMsgContent());
}
}

就完了！

我犯的一个致命错误：item布局的height设置成了match_parent导致debug了一小时，耻辱

效果图：（我这里是点击添加一个对话，点击添加一个，即时通讯这里先不实现）



全部代码

package com.example.wechat.adapter;

import android.content.Context;
import android.content.Intent;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.bumptech.glide.Glide;
import com.example.wechat.R;
import com.example.wechat.bean.ChatDetailBean;
import com.example.wechat.bean.ChatItemBean;
import com.example.wechat.chat.ChatActivity;

import java.util.List;

import static com.example.wechat.R.id.view;

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

private List<ChatDetailBean> list;

public ChatDetailAdapter(List<ChatDetailBean> list) {
this.list = list;
}

private Context context = null;

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (context == null) {
context = parent.getContext();
}
if (viewType == TYPE_ME) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_rv_chat_me, parent, false);
return new MeViewHolder(view);
} else {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_rv_chat_friend, parent, false);
return new FriendViewHolder(view);
}
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof MeViewHolder) {
((MeViewHolder) holder).mTvMyMsg.setText(list.get(position).getMsgContent());
} else {
((FriendViewHolder) holder).mTvFriendMsg.setText(list.get(position).getMsgContent());
}
}

private static final int TYPE_ME = 0;
private static final int TYPE_FRIEND = 1;

@Override
public int getItemViewType(int position) {
return list.get(position).getMsgType();
}

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

private static class MeViewHolder extends RecyclerView.ViewHolder {
TextView mTvMyMsg;
ImageView mIvMyAvatar;

public MeViewHolder(View view) {
super(view);
mTvMyMsg = (TextView) view.findViewById(R.id.tv_my_msg);
mIvMyAvatar = (ImageView) view.findViewById(R.id.iv_my_avatar);
}
}

private static class FriendViewHolder extends RecyclerView.ViewHolder {
TextView mTvFriendMsg;
ImageView mIvFriendAvatar;

public FriendViewHolder(View view) {
super(view);
mTvFriendMsg = (TextView) view.findViewById(R.id.tv_friend_msg);
mIvFriendAvatar = (ImageView) view.findViewById(R.id.iv_friend_avatar);
}
}
}