我正在创建一个聊天的android应用程序。在这个应用程序中有一个函数JSON_DATA_WEB_CALL，它使用volley库从url中提取数据，然后在这个recyclelerview中显示它。在onCreate()方法中有一个重复的线程运行JSON_DATA_WEB_CALL()方法。这是每1秒后重新加载消息的方式，但是当我滚动recyclerview时它返回到相同的位置（顶部），因此滚动不起作用。
messages.java
public class messages extends Activity {
TextView mTitle;
List<ConversationsList> conversationsList;
RecyclerView recyclerView;
RecyclerView.LayoutManager recyclerViewlayoutManager;
RecyclerView.Adapter recyclerViewadapter;
ProgressBar progressBar;
String HTTP_JSON_URL = "http://xxx.xx/conversate.php";
String GET_JSON_FROM_SERVER_NAME = "my_name";
String GET_JSON_FROM_SERVER_NAME2 = "imageurl";
String GET_JSON_FROM_SERVER_NAME3 = "friend_uid";
String GET_JSON_FROM_SERVER_NAME4 = "friend_name";
String GET_JSON_FROM_SERVER_NAME5 = "time";
String GET_JSON_FROM_SERVER_NAME6 = "my_uid";
String GET_JSON_FROM_SERVER_NAME7 = "message";
JsonArrayRequest jsonArrayRequest ;
ScrollView scrollView;
Context context;
Intent intent;
RequestQueue requestQueue ;
int count = 1;
ArrayList<String> FriendNames;
ImageButton sendbutton;
EditText edit;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_message);
mTitle = findViewById(R.id.profiletitle);
edit = findViewById(R.id.message);
Typeface face = Typeface.createFromAsset(getAssets(),
"fonts/epimodem.ttf");
Typeface face2 = Typeface.createFromAsset(getAssets(),
"fonts/epimodem2.ttf");
edit.setTypeface(face);
mTitle.setTypeface(face2);
conversationsList = new ArrayList<>();
progressBar = findViewById(R.id.progressBarc);
recyclerView = findViewById(R.id.recyclerViewc);
progressBar.setVisibility(View.VISIBLE);
recyclerView.setHasFixedSize(true);
recyclerViewlayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(recyclerViewlayoutManager);
// **********************************************************************
FriendNames = new ArrayList<>();
Thread t = new Thread() {
@Override
public void run() {
try {
while (!isInterrupted()) {
Thread.sleep(1000);
runOnUiThread(new Runnable() {
@Override
public void run() {
JSON_DATA_WEB_CALL();
conversationsList.clear();
}
});
}
} catch (InterruptedException e) {
}
}
};
if(!conversationsList.isEmpty()){
recyclerView.scrollToPosition(conversationsList.size() - 1);
}
t.start();
}
public void JSON_DATA_WEB_CALL() {
jsonArrayRequest = new JsonArrayRequest(HTTP_JSON_URL,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
progressBar.setVisibility(View.GONE);
JSON_PARSE_DATA_AFTER_WEBCALL(response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
requestQueue = Volley.newRequestQueue(this);
requestQueue.add(jsonArrayRequest);
}
public void JSON_PARSE_DATA_AFTER_WEBCALL(final JSONArray array){
try {
recyclerView.getRecycledViewPool().clear();
for (int i = 0; i < array.length(); i++) {
ConversationsList GetDataAdapter1 = new ConversationsList();
JSONObject json;
json = array.getJSONObject(i);
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
String my_uid = user.getUid();
intent = getIntent();
String check = json.getString(GET_JSON_FROM_SERVER_NAME3);
String check2 = json.getString(GET_JSON_FROM_SERVER_NAME6);
String friend_uid = intent.getExtras().getString("Uid");
if ((check.contains(friend_uid) && my_uid.contains(check2)) || (check.contains(my_uid) && check2.contains(friend_uid)) && !"".equals(json.getString(GET_JSON_FROM_SERVER_NAME7))) {
GetDataAdapter1.setmy_name(json.getString(GET_JSON_FROM_SERVER_NAME));
GetDataAdapter1.setfriend_name(json.getString(GET_JSON_FROM_SERVER_NAME4));
GetDataAdapter1.setmy_uid(json.getString(GET_JSON_FROM_SERVER_NAME6));
GetDataAdapter1.setfriend_uid(json.getString(GET_JSON_FROM_SERVER_NAME3));
GetDataAdapter1.setimageurl(json.getString(GET_JSON_FROM_SERVER_NAME2));
GetDataAdapter1.setmessage(json.getString(GET_JSON_FROM_SERVER_NAME7));
GetDataAdapter1.settime(json.getString(GET_JSON_FROM_SERVER_NAME5));
FriendNames.add(json.getString(GET_JSON_FROM_SERVER_NAME));
FriendNames.add(json.getString(GET_JSON_FROM_SERVER_NAME7));
FriendNames.add(json.getString(GET_JSON_FROM_SERVER_NAME2));
FriendNames.add(json.getString(GET_JSON_FROM_SERVER_NAME3));
FriendNames.add(json.getString(GET_JSON_FROM_SERVER_NAME4));
FriendNames.add(json.getString(GET_JSON_FROM_SERVER_NAME5));
FriendNames.add(json.getString(GET_JSON_FROM_SERVER_NAME6));
conversationsList.add(GetDataAdapter1);
recyclerViewadapter = new ConversationsRecyclerAdapter(conversationsList, context);
recyclerView.setAdapter(recyclerViewadapter);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
public void send_messages(View v)
{ Intent intent = getIntent();
String imageurl ="";
String friend_name=intent.getExtras().getString("Name");
String friend_uid =intent.getExtras().getString("Uid");
EditText et;
et = findViewById(R.id.message);
String message = et.getText().toString();
String time = DateFormat.getDateTimeInstance().format(new Date());
imageurl =intent.getExtras().getString("Imageurl");
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
if (user != null) {
String my_name = user.getDisplayName();
if("".equals(my_name)){
String mEmail = user.getEmail();
int iend = mEmail.indexOf("@");
if(iend != -1)
{
my_name = mEmail.substring(0,iend);
}
}
String my_uid = user.getUid();
String method = "message";
backgroundtask bgtask = new backgroundtask(this);
bgtask.execute(method,my_name,my_uid,friend_name,friend_uid,imageurl,time,message);
recyclerView.scrollToPosition(conversationsList.size() - 1);
}
}
}
MessagesRecyclerAdapter.java
public class MessagesRecyclerAdapter extends RecyclerView.Adapter<MessagesRecyclerAdapter.ViewHolder1>{
Context context;
Context ctx;
List<MessagesList> MessagesList;
public MessagesRecyclerAdapter(List<MessagesList> getDataAdapter1, Context context){
super();
this.MessagesList = getDataAdapter1;
this.context = context;
}
@Override
public ViewHolder1 onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview_messages, parent, false);
return new ViewHolder1(view);
}
@Override
public void onBindViewHolder(final ViewHolder1 holder, int position) {
ImageView ImageUrl1 = holder.ImageUrl;
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
MessagesList getDataAdapter1 = MessagesList.get(position);
final String Name = getDataAdapter1.getFriend_name();
final String Uid = getDataAdapter1.getfrienduid();
final String Imageurlserver = getDataAdapter1.getImageurl();
final String Imageurlserve = user.getPhotoUrl().toString();
holder.FriendName.setText(getDataAdapter1.getFriend_name());
if(!"".equals(Imageurlserver))
{Picasso.with(context).load(Imageurlserver).into(ImageUrl1);}
else{
ImageUrl1.setImageResource(R.drawable.profile);
}
holder.button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent;
intent = new Intent(context, messages.class);
intent.putExtra("Name", Name);
intent.putExtra("Uid",Uid);
intent.putExtra("Imageurl",Imageurlserve);
context.startActivity(intent);
}
});
}
@Override
public int getItemCount() {
return MessagesList.size();
}
class ViewHolder1 extends RecyclerView.ViewHolder{
public TextView FriendName;
public ImageView ImageUrl;
public Button button;
public ViewHolder1(View itemView) {
super(itemView);
Typeface face = Typeface.createFromAsset(itemView.getContext().getAssets(),
"fonts/epimodem.ttf");
Typeface face2 = Typeface.createFromAsset(itemView.getContext().getAssets(),
"fonts/epimodem2.ttf");
FriendName = itemView.findViewById(R.id.MessageCard6); this.FriendName.setTypeface(face);
ImageUrl = itemView.findViewById(R.id.Messagepic);
button = itemView.findViewById(R.id.send_message);
}
}
}
答案 0 :(得分：0)
conversationsList 之前清除JSON_DATA_WEB_CALL()
public void run() {
conversationsList.clear();
JSON_DATA_WEB_CALL();
}
答案 1 :(得分：0)
每次刷新数据时都不要设置新适配器。创建适配器一次，然后在此适配器中设置conversationsList并调用notifyDataSetChanged