1.聊天界面
在app/build.gradle中添加依赖库
implementation'com.android.support:recyclerview-v7:28.0.0'
修改activity_mian_xml代码
1.android.support.v7.widget.RecyclerView 的完整包路径。
定义实体类Msg content表示内容 ，type表示类型：发送，接收。
public class Msg {
public static final int TYPE_RECEIVED=0;
public static final int TYPE_SENT=0;
private Stringcontent;
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;
}
}
新建一个item.xml 为RecyclerVIew的子项
包含两个对话图片用两个（Linearlayout）
创建RecyclerVIew的适配器MsgAdapter
public class MsgAdapterextends RecyclerView.Adapter {
private List<Msg> mMsglist;
static class ViewHolderextends RecyclerView.ViewHolder{//避免findviewbyid重复注册
LinearLayoutleftLayout;//成员变量
LinearLayoutrightLayout;
TextViewleftmsg;
TextViewrightmsg;
public ViewHolder(View view){//封装到Viewholder里面
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;//把要展示的数据赋值给全局变量
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent,int viewType) {//oncreate创建Viewholder的实例
View view=LayoutInflater.from(prent.getContext()).inflate(R.layout.msg_item,parent,false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder,int position) {bin方法是对子项数据赋值
Msg msg=mMsglist.get(position);
if(msg.getType()==Msg.TYPE_RECEIVED){
holder.leftLayout.setVisibility(View.VISIBLE);//显示
holder.rightLayout.setVisibility(View.GONE);//不显示
holder.leftmsg.setText(msg.getContent());
}else if(msg.getType()==Msg.TYPE_SENT){
holder.leftLayout.setVisibility(View.GONE);
holder.rightLayout.setVisibility(View.VISIBLE);
holder.rightmsg.setText(msg.getContent());
}
}
@Override
public int getItemCount() {//告诉我们一共有多少子项
return mMsglist.size();
}
}
最后是MainActivity中的代码
public class MainActivityextends AppCompatActivity {
private List <Msg>msgList=new ArrayList<>();//泛型类
private EditText inputText;
private Button send;
private RecyclerView msgRecyclerView;
private MsgAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
inirMsgs();//初始化数据
inputText=(EditText)findViewById(R.id.input_text);
send=(Button)findViewById(R.id.send);
msgRecyclerView=(RecyclerView)findViewById(R.id.msg_parent);
LinearLayoutManager layoutManager=new LinearLayoutManager(this);
msgRecyclerView.setAdapter(adapter);//绑定适配器
Log.d("MainActivity" ,"adpter");
send.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String content=inputText.getText().toString();
if(!"".equals(content)){
Msg msg=new Msg(content,Msg.TYPE_SENT);
msgList.add(msg);
adapter.notifyItemInserted(msgList.size()-1);//新数据插入
msgRecyclerView.scrollToPosition(msgList.size()-1);//定位到最后一行
inputText.setText("");//清空数据
}
Toast.makeText(MainActivity.this,"true",Toast.LENGTH_SHORT).show();
}
});
}
private void inirMsgs(){
Msg msg1=new Msg("1",Msg.TYPE_RECEIVED);
msgList.add(msg1);
Msg msg2=new Msg("2",Msg.TYPE_SENT);
msgList.add(msg2);
Msg msg3=new Msg("3",Msg.TYPE_RECEIVED);
msgList.add(msg3);
}
}
logcat日志显示错误：No adapter attached; skipping layout
1.没有绑定适配器 setAdpter（）已绑定
2.布局设置成RelativeLayout 没有用
3.使用 msgRecyclerView.setLayoutManager(layoutManager);无用
解决 private MsgAdapter adapter;定义全局变量
MsgAdapter adapter=new MsgAdapter(msgList);//创建adpter的实例
