我正在尝试排球，所以它对我的项目非常有用。我可以添加内容并移动信息，但我需要在将新项目添加到列表时刷新或更新自己，我个人希望像Whatsapp一样顺利。
我怎样才能做到这一点？我有另一个项目，我使用AsyncTask，但我不知道这是否应该采取这种方法。我对Android开发有点新意，这对Volley有点了解。
你能帮助我并指出正确的方向吗？
以下是我的适配器的代码，我的主要活动以及我发布帖子的位置。我相信这个刷新应该在这3个类中的一个中完成。
如果你能帮助我，那将是我所知道的一个重要的学习步骤。我感谢那些愿意帮助的人！
谢谢！ ：）
MainActivity
public class MainActivity extends AppCompatActivity implements NewsAdapter.OnItemClickListener{
//variable to hold the information that we want to pass to another activity
public static final String EXTRA_NEWS = "newspost";
private TextView textviewUsername, textviewUserEmail;
ArrayList<News> newsArrayList;
private LinearLayoutManager mLayoutManager;
RecyclerView recyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (!SharedPrefManager.getInstance(this).isLoggedIn()){
startActivity(new Intent(this, LoginActivity.class));
finish();
}
textviewUsername = findViewById(R.id.txtViewusername);
textviewUserEmail = findViewById(R.id.txtViewUserEmail);
textviewUsername.setText(SharedPrefManager.getInstance(this).getUser().getUsername());
textviewUserEmail.setText(SharedPrefManager.getInstance(this).getUser().getEmail());
recyclerView = findViewById(R.id.recylerView);
mLayoutManager = new LinearLayoutManager(getApplicationContext());
//Invert the view of the list
mLayoutManager.setReverseLayout(true);
mLayoutManager.setStackFromEnd(true);
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setHasFixedSize(true);
recyclerView.setItemAnimator(new DefaultItemAnimator());
newsArrayList = new ArrayList<>();
loadProducts();
}
private void loadProducts() {
/*
* Creating a String Request
* The request type is GET defined by first parameter
* The URL is defined in the second parameter
* Then we have a Response Listener and a Error Listener
* In response listener we will get the JSON response as a String
* */
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, Constants.URL_SHOW_NEWS, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
//converting the string to json array object
JSONArray jsonArray = response.getJSONArray("news");
//traversing through all the object
for (int i = 0; i < jsonArray.length(); i++) {
//getting product object from json array
JSONObject jsnews = jsonArray.getJSONObject(i);
//adding the product to product list
String post = jsnews.getString("noticia");
newsArrayList.add(new News(post));
}
//creating adapter object and setting it to recyclerview
NewsAdapter adapter = new NewsAdapter(MainActivity.this, newsArrayList);
recyclerView.setAdapter(adapter);
/* ------ SETTING OUR ADAPTER TO OUR ONCLICKLISTERNER ---------*/
adapter.setOnClickListener(MainActivity.this);
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Parou aqui", Toast.LENGTH_LONG).show();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), "Algo de errad nao esta certo", Toast.LENGTH_LONG).show();
}
});
//adding our stringrequest to queue
Volley.newRequestQueue(this).add(request);
}
public void post(View view){
startActivity(new Intent(this, PostNews.class));
}
@Override
public void onItemClick(int position) {
/* -------------- DO WHATEVER YOU WANT WITH THE CLICK EVENT HERE------------------ */
Intent newsDetail = new Intent(this, NewsDetailActivity.class);
News clickedNews = newsArrayList.get(position);
newsDetail.putExtra(EXTRA_NEWS, clickedNews.getNews_post());
startActivity(newsDetail);
}
}
我的适配器
public class NewsAdapter extends RecyclerView.Adapter<NewsAdapter.NewsAdapterViewHolder> {
private Context context;
private ArrayList<News> newsArrayList;
//creating a listener for the interface with the same name as our interface
private OnItemClickListener xListener;
//making our own custom onClickListener
public interface OnItemClickListener {
void onItemClick(int position);
}
public void setOnClickListener(OnItemClickListener listener){
//used to simulate the onItemClick of a listview
xListener = listener;
}
public NewsAdapter(Context context, ArrayList<News> newsArrayList) {
this.context = context;
this.newsArrayList = newsArrayList;
}
@Override
public NewsAdapterViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(context).inflate(R.layout.news_list, parent, false);
return new NewsAdapterViewHolder(v);
}
@Override
public void onBindViewHolder(NewsAdapterViewHolder holder, int position) {
News currentNews = newsArrayList.get(position);
String post = currentNews.getNews_post();
holder.txtNoticia.setText(post);
}
@Override
public int getItemCount() {
return newsArrayList.size();
}
public class NewsAdapterViewHolder extends RecyclerView.ViewHolder{
public TextView txtNoticia;
public NewsAdapterViewHolder(View itemView) {
super(itemView);
txtNoticia = itemView.findViewById(R.id.txtnewsPost);
//creating the option for when we click on something to work
//-------------------------WARNING--------------------------//
/*THIS IS A TRICK TO USE onItemClick AS YOU WOULD USE IN A LIST VIEW
* IT'S BETTER TO USE HERE (ACCORDING TO THE TUTORIAL THAN USING ON THE *-onBindViewHolder-*)*/
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (xListener != null) {
int position = getAdapterPosition();
//noposition to make sure the position is still valid
if (position != RecyclerView.NO_POSITION){
//onItemclick is the method that we created on the interface
xListener.onItemClick(position);
}
}
}
});
}
}
}
创建帖子的活动
public class PostNews extends AppCompatActivity {
private Button btnpostar;
private EditText editTextNewsPost;
private ProgressBar progressBar;
SharedPrefManager sharedPrefManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_post_news);
editTextNewsPost = findViewById(R.id.EditTextNewsPost);
btnpostar = findViewById(R.id.btnPostar);
progressBar = findViewById(R.id.progressBar3);
progressBar.setVisibility(View.GONE);
}
public void salvarNoticia(View view) {
final User user = sharedPrefManager.getInstance(this).getUser();
final String post = editTextNewsPost.getText().toString();
if (!post.equals("")) {
progressBar.setVisibility(View.VISIBLE);
StringRequest stringRequest = new StringRequest(Request.Method.POST,
Constants.URL_REGISTER_NEWS,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
progressBar.setVisibility(View.GONE);
try {
JSONObject jsonObject = new JSONObject(response);
Toast.makeText(getApplicationContext(), jsonObject.getString("message"),
Toast.LENGTH_LONG).show();
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_LONG).show();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
progressBar.setVisibility(View.GONE);
Toast.makeText(getApplicationContext(), "Erro: " + error.getMessage(), Toast.LENGTH_LONG).show();
}
}) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> params = null;
params = new HashMap<>();
params.put("news_post", post);
params.put("user_FK", String.valueOf(user.getId()));
return params;
}
};
RequestHandler.getInstance(getApplicationContext()).addToRequestQueue(stringRequest);
} else {
Toast.makeText(getApplicationContext(), "Por favor, não poste nada em branco", Toast.LENGTH_LONG).show();
}
}
}
答案 0 :(得分：3)
这个问题不受特定编程问题的影响，而是指向应用程序架构。但是，我正在写这个答案，分享我使用这些应用程序的一些经验。
据我所知，您希望使用RecyclerView在Feed中显示应用中的帖子。当用户从应用程序创建帖子/产品或其他人创建帖子/产品时，需要更新RecyclerView。如果我理解正确，那么你需要记住以下事项。
loadProducts(); onCreate函数中的MainActivity函数，该函数是正确的。应用程序应加载启动时需要在RecyclerView中显示的所有项目。所以初始化部分完全没问题。 RecyclerView。当用户想要查看是否有任何更新时，他/她可能会下拉RecyclerView来刷新数据。我想你已经想到了这一点，我只是涵盖了所有可用的选项。 loadProducts函数。当您的每个拉取请求都有新数据时，请使用RecyclerView方法相应地更新notifyDataSetChanged。 loadProducts函数并相应地更新RecyclerView。推动既不是实时也不可靠。但是，它可能会为您节省大量的API调用。 我刚给你一些想法。希望这些可以帮到你。
<强>更新
根据你的评论，我认为你没有清楚地告诉我。从服务器端开始每隔x分钟就无法获得推送通知，因为在这种情况下，您需要在用户设备中安装的每个应用程序中跟踪帖子更新的跟踪 - 这是一个可怕的设计。
你需要选一个。如果您想每x分钟刷新一次数据，那么我建议您在应用程序中保留Handler或后台Service，每x分钟后调用一次loadProducts功能更新您的数据。
如果您计划实施基于推送通知的更新，则将推送发送到连接在服务器端插入的每个新数据上的设备。当在应用程序端收到推送时，您需要使用更新的数据相应地更新列表。希望现在更清楚了。