[英]how to auto update RecyclerView.Adapter in android?
這是我的代碼:
public class ItemsListActivity extends AppCompatActivity {
private List<AllItems> listItems;
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_items_list);
Button camera=(Button)findViewById(R.id.camera);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
listItems = new ArrayList<>();
camera.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(ItemsListActivity.this, Camera.class);
startActivity(i);
}
});
getData();
}
private void getData(){
final ProgressDialog loading = ProgressDialog.show(this,"Loading Data", "Please wait...",false,false);
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Config.DATA_URL,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
loading.dismiss();
parseData(response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(jsonArrayRequest);
}
private void parseData(JSONArray array){
for(int i = 0; i<array.length(); i++) {
AllItems items = new AllItems();
JSONObject json = null;
try {
json = array.getJSONObject(i);
items.setImageUrl(json.getString(Config.TAG_IMAGE_URL));
items.setName(json.getString(Config.TAG_NAME));
} catch (JSONException e) {
e.printStackTrace();
}
listItems.add(items);
}
adapter = new CardAdapter(listItems, this);
recyclerView.setAdapter(adapter);
adapter.notifyItemRangeChanged(0, listItems.size());
}
}
這是CardAdapter:
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> {
private ImageLoader imageLoader;
private Context context;
List<AllItems> superHeroes;
public CardAdapter(List<AllItems> superHeroes, Context context){
super();
this.superHeroes = superHeroes;
this.context = context;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.all_items_lists, parent, false);
ViewHolder viewHolder = new ViewHolder(v);
return viewHolder;
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
AllItems superHero = superHeroes.get(position);
imageLoader = CustomVolleyRequest.getInstance(context).getImageLoader();
imageLoader.get(superHero.getImageUrl(), ImageLoader.getImageListener(holder.imageView, R.mipmap.ic_launcher, android.R.drawable.ic_dialog_alert));
holder.imageView.setImageUrl(superHero.getImageUrl(), imageLoader);
holder.textViewName.setText(superHero.getName());
}
@Override
public int getItemCount() {
return superHeroes.size();
}
class ViewHolder extends RecyclerView.ViewHolder{
public NetworkImageView imageView;
public TextView textViewName;
public ViewHolder(View itemView) {
super(itemView);
imageView = (NetworkImageView) itemView.findViewById(R.id.imageViewHero);
textViewName = (TextView) itemView.findViewById(R.id.textViewName);
}
}
}
如何更新適配器數據以顯示新接收的項目?
每次解析數據時都在創建適配器的實例,只需在onCreate()方法中一次創建它的實例,如下所示:
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
listItems = new ArrayList<>();
adapter = new CardAdapter(listItems, this);
recyclerView.setAdapter(adapter);
然后只需將您的解析數據通知適配器,如下所示:
listItems.add(items);
adapter.notifyDataSetChanged();
將為您工作。
在這里,每次調用getData()都在重新初始化適配器時,會發生什么情況。 相反,您應該在onCreate和getData中初始化適配器,只需更新要在適配器中傳遞的列表並調用adapter.notifyDataSetChanged()。
private List<AllItems> listItems;
private RecyclerView recyclerView; private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_items_list); Button camera=(Button)findViewById(R.id.camera); recyclerView = (RecyclerView) findViewById(R.id.recyclerView); recyclerView.setHasFixedSize(true); layoutManager = new LinearLayoutManager(this); recyclerView.setLayoutManager(layoutManager); listItems = new ArrayList<>();
adapter = new CardAdapter(listItems, this);
recyclerView.setAdapter(adapter);
camera.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Intent i = new Intent(ItemsListActivity.this, Camera.class); startActivity(i); } }); getData(); }
private void getData(){
final ProgressDialog loading = ProgressDialog.show(this,"Loading Data", "Please wait...",false,false);
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Config.DATA_URL, new Response.Listener<JSONArray>() { @Override public void onResponse(JSONArray response) { loading.dismiss(); parseData(response); }
}, new Response.ErrorListener() {
@Override public void onErrorResponse(VolleyError error) { } }); RequestQueue requestQueue = Volley.newRequestQueue(this); requestQueue.add(jsonArrayRequest); }
private void parseData(JSONArray array){
for(int i = 0; i<array.length(); i++) {
AllItems items = new AllItems(); JSONObject json = null;
try
{
json = array.getJSONObject(i); items.setImageUrl(json.getString(Config.TAG_IMAGE_URL)); items.setName(json.getString(Config.TAG_NAME)); } catch (JSONException e) { e.printStackTrace(); } listItems.add(items); }
}
adapter.notifyDataSetChanged().
}
如果您不想顯示以前的項目,請在添加新項目之前調用lisItems.clear()。
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