[英]how to clear RecyclerView adapter data
在我的 UI 中,我使用了两个按钮将不同的数据加载到 RecyclerView。 第一次单击每个按钮时数据正确显示。 但是,如果我第二次单击该按钮,数据将两次添加到适配器中。 我的意思是适配器没有被清除。 单击按钮继续添加数据。 我想我必须通过单击按钮对适配器做一些事情。 任何人都可以让我知道如何清除适配器或我哪里出错了..
这是代码。
public class GstVendorLocRetrieve extends AppCompatActivity {
private String vault;
private TextView txt;
public static final String DATA_URL = "http://oursite.com/getgstvendorlocation.php?vault_no=";
public static final String DATA_URL1 = "http://oursite.com/getgstcustomerlocation.php?vault_no=";
//Tags for my JSONRes
public static final String TAG_VendorID = "VendorID";
public static final String TAG_CustomerID = "Customer_ID";
public static final String TAG_ADDRESS = "Address";
private Button vendor;
private Button customer;
//Creating a List of superheroes
private List<GstVendLoc> listSuperHeroes;
private List<GstCustLoc> listSuperHeroes1;
//Creating Views
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.locationretrieve);
SharedPreferences sharedPreferences = getSharedPreferences(GstLogin.SHARED_PREF_NAME, MODE_PRIVATE);
vault = sharedPreferences.getString(GstLogin.EMAIL_SHARED_PREF,"Not Available");
vendor = (Button) findViewById(R.id.login);
customer = (Button) findViewById(R.id.login1);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
//Initializing our superheroes list
listSuperHeroes = new ArrayList<>();
listSuperHeroes1 = new ArrayList<>();
vendor.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
recyclerView.setAdapter(null);
getData();
}
});
customer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
recyclerView.setAdapter(null);
getData1();
}
});
}
//This method will get data from the web api
private void getData(){
//Showing a progress dialog
final ProgressDialog loading = ProgressDialog.show(this,"Loading Data", "Please wait...",false,false);
//Creating a json array request
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(DATA_URL+vault,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
//Dismissing progress dialog
loading.dismiss();
//calling method to parse json array
parseData(response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
//Creating request queue
RequestQueue requestQueue = Volley.newRequestQueue(this);
//Adding request to the queue
requestQueue.add(jsonArrayRequest);
}
//This method will parse json data
private void parseData(JSONArray array){
for(int i = 0; i<array.length(); i++) {
GstVendLoc gst1 = new GstVendLoc();
JSONObject json = null;
try {
json = array.getJSONObject(i);
gst1.setVendorID(json.getString(TAG_VendorID));
gst1.setAddress(json.getString(TAG_ADDRESS));
} catch (JSONException e) {
e.printStackTrace();
}
listSuperHeroes.add(gst1);
}
//Finally initializing our adapter
adapter = new CardAdapter17(listSuperHeroes, this);
//Adding adapter to recyclerview
recyclerView.setAdapter(adapter);
}
private void getData1(){
//Showing a progress dialog
final ProgressDialog loading = ProgressDialog.show(this,"Loading Data", "Please wait...",false,false);
//Creating a json array request
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(DATA_URL1+vault,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
//Dismissing progress dialog
loading.dismiss();
//calling method to parse json array
parseData1(response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
//Creating request queue
RequestQueue requestQueue = Volley.newRequestQueue(this);
//Adding request to the queue
requestQueue.add(jsonArrayRequest);
}
//This method will parse json data
private void parseData1(JSONArray array){
for(int i = 0; i<array.length(); i++) {
GstCustLoc gst1 = new GstCustLoc();
JSONObject json = null;
try {
json = array.getJSONObject(i);
gst1.setCustomer_ID(json.getString(TAG_CustomerID));
gst1.setAddress(json.getString(TAG_ADDRESS));
} catch (JSONException e) {
e.printStackTrace();
}
listSuperHeroes1.add(gst1);
}
//Finally initializing our adapter
adapter = new CardAdapter18(listSuperHeroes1, this);
//Adding adapter to recyclerview
recyclerView.setAdapter(adapter);
}
}
使用此代码清除 RecycleView 项目
public void clear() {
int size = listSuperHeroes.size();
listSuperHeroes.clear();
notifyItemRangeRemoved(0, size);
}
您需要在第二次获取数据之前清除您的Array List
。
在for loop
之前在parseData1
方法中执行此parseData1
。
listSuperHeroes.clear();
listSuperHeroes1.clear();
您需要做的是在按钮上更新 RecyclerView 单击,将下面的方法放入您的适配器中
public void updateData(ArrayList<ViewModel> viewModels) {
items.clear();
items.addAll(viewModels);
notifyDataSetChanged();
}
比用新数据调用这个方法
ArrayList<ViewModel> viewModelsWithNewData = new ArrayList<ViewModel>();
adapter.updateData(viewModelsWithNewData );
从网上获取数据后,您不需要设置适配器
//Finally initializing our adapter
adapter = new CardAdapter18(listSuperHeroes1, this);
//Adding adapter to recyclerview
recyclerView.setAdapter(adapter);
您可以在创建时初始化或设置适配器,并在'listSuperHeroes1'
添加数据,解析数据后,您可以执行adapter.notifyDataSetChanged();
这将更改列表数据。
以及获取先前数据的解决方案,您必须从listsuperHeroes1
删除所有数据,如果您遇到任何问题,请发表评论。
我只是在改进@Rony 的回答。 如果您应该在尝试调用.size()
之前始终检查 ArrayList 是否不为空,否则最终可能会出现空指针异常
if (listSuperHeroes != null && !listSuperHeroes.isEmpty()) {
int size = listSuperHeroes.size();
listSuperHeroes.clear();
notifyItemRangeRemoved(0, size);
}
recyclerView.setAdapter(null);
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