package com.itheima74.chatui;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.View;import android.widget.Button;import android.widget.EditText;import java.util.ArrayList;/** * 聊天界面,使用recyclerview實現(xiàn) * 效果不好,發(fā)送的消息不能靠右對齊, * 不知何故,怎么弄都弄不好,請教! * 問題的解決:用Relativelayout代替linearlayout可以解決上述問題 */public class MainActivity extends AppCompatActivity { private RecyclerView recyclerview; private EditText et_input; private ArrayList<Msg> mMsgList; private MsgAdapter mMsgAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); initData(); initAdapter(); } private void initAdapter() { mMsgAdapter = new MsgAdapter(mMsgList); recyclerview.setAdapter(mMsgAdapter); } /** * 初始化數(shù)據(jù)源 */ private void initData() { mMsgList = new ArrayList<>(); mMsgList.add(new Msg("Hello!", Msg.TYPE_RECEIVE)); mMsgList.add(new Msg("Hello! Who is that?", Msg.TYPE_SEND)); mMsgList.add(new Msg("This is Jack,Nice to meet you!", Msg.TYPE_RECEIVE)); } /** * 初始化控件 */ private void initView() { recyclerview = (RecyclerView) findViewById(R.id.recyclerview); et_input = (EditText) findViewById(R.id.et_input); Button bt_send = (Button) findViewById(R.id.bt_send); LinearLayoutManager layoutManager = new LinearLayoutManager(this); layoutManager.setOrientation(LinearLayoutManager.VERTICAL); recyclerview.setLayoutManager(layoutManager); bt_send.setOnClickListener(new View.OnClickListener() {  @Override  public void onClick(View v) {  String content = et_input.getText().toString().trim();  // 如果用戶沒有輸入,則是一個空串""  if (!content.isEmpty()) {   mMsgList.add(new Msg(content, Msg.TYPE_SEND));   // 通知數(shù)據(jù)適配器刷新界面   mMsgAdapter.notifyDataSetChanged();   // 定位到最后一行   recyclerview.scrollToPosition(mMsgList.size() - 1);   // 輸入框置空   et_input.setText("");  }  } }); }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#d8e0e8" android:orientation="vertical"> <android.support.v7.widget.RecyclerView android:id="@+id/recyclerview" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1" /> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <EditText  android:id="@+id/et_input"  android:layout_width="0dp"  android:layout_height="wrap_content"  android:layout_weight="1"  android:hint="請輸入要發(fā)送的內(nèi)容" /> <Button  android:id="@+id/bt_send"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text="發(fā)送" /> </LinearLayout></LinearLayout>

package com.itheima74.chatui;/** * Created by My on 2017/3/3. */class Msg { static final int TYPE_RECEIVE = 1; static final int TYPE_SEND = 2; String content; int type; Msg(String content, int type) { this.content = content; this.type = type; }}

package com.itheima74.chatui;import android.support.v7.widget.RecyclerView;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;import java.util.ArrayList;/** * Created by My on 2017/3/3. */class MsgAdapter extends RecyclerView.Adapter<MsgAdapter.ViewHolder> { private ArrayList<Msg> mMsgList; MsgAdapter(ArrayList<Msg> mMsgList) { this.mMsgList = mMsgList; } @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View view = View.inflate(parent.getContext(), R.layout.recyclerview_item, null); return new ViewHolder(view); } @Override public void onBindViewHolder(ViewHolder holder, int position) { Msg msg = mMsgList.get(position); if (msg.type == Msg.TYPE_RECEIVE) {  holder.tv_receive.setVisibility(View.VISIBLE);  holder.tv_send.setVisibility(View.GONE);  holder.tv_receive.setText(msg.content); } else {  holder.tv_send.setVisibility(View.VISIBLE);  holder.tv_receive.setVisibility(View.GONE);  holder.tv_send.setText(msg.content); } } @Override public int getItemCount() { return mMsgList.size(); } static class ViewHolder extends RecyclerView.ViewHolder { private TextView tv_receive; private TextView tv_send; ViewHolder(View itemView) {  super(itemView);  tv_receive = (TextView) itemView.findViewById(R.id.tv_receive);  tv_send = (TextView) itemView.findViewById(R.id.tv_send); } }}

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:padding="10dp"> <TextView android:id="@+id/tv_receive" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="@drawable/message_left" android:gravity="center" android:text="who?" android:textSize="20sp" /> <TextView android:id="@+id/tv_send" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_below="@id/tv_receive" android:background="@drawable/message_right" android:gravity="center" android:text="i am your father" android:textSize="20sp" /></RelativeLayout>