我在我的应用程序中添加了一个溢出菜单，因此当用户按下菜单中的“删除”项目之一时，他们添加到回收站视图中的所有卡片视图都将被删除。
我读到我可以去做类似的事情
productList.clear();
因此我将其插入到溢出菜单代码中，但是当我按下按钮时，什么也没发生。
create.java（主要活动）
public class create extends AppCompatActivity {
//a list to store all the products
List<Product> productList;
//the recyclerview
RecyclerView recyclerView;
Product mProduct;
private Map<String, String> numberItemValues = new HashMap<>();
private Map<Integer, Integer> mSpinnerSelectedItem = new HashMap<Integer, Integer>();
// RelativeLayout relativeLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.create);
findViewById(R.id.relativeLayout).requestFocus();
findViewById(R.id.relativeLayout).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
InputMethodManager imm = (InputMethodManager) view.getContext()
.getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}
});
//opens csv
InputStream inputStream = getResources().openRawResource(R.raw.shopitems);
CSVFile csvFile = new CSVFile(inputStream);
final List<String> mSpinnerItems = csvFile.read();
//getting the recyclerview from xml
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
//initializing the productlist
productList = new ArrayList<>();
productList.add(new Product(mSpinnerItems, "Test Edit Text",false, "Text String 2"));
final ProductAdapter adapter = new ProductAdapter(this, productList, numberItemValues);
//TODO FAB BUTTON
FloatingActionButton floatingActionButton =
findViewById(R.id.fab);
floatingActionButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
productList.add(mProduct);
if(adapter != null)
adapter.notifyDataSetChanged();
//Handle the empty adapter here
}
});
//setting adapter to recyclerview
recyclerView.setAdapter(adapter);
}
//TODO OVERFLOW MENU
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_delete) {
((ProductAdapter) recyclerView.getAdapter()).reset();
return true;
}
return super.onOptionsItemSelected(item);
}
private class CSVFile {
InputStream inputStream;
public CSVFile(InputStream inputStream) {
this.inputStream = inputStream;
}
public List<String> read() {
List<String> resultList = new ArrayList<String>();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
String line;
while ((line = reader.readLine()) != null) {
String[] row = line.split(",");
//TODO I edited this part so that you'd add the values in our new hash map variable
numberItemValues.put(row[1], row[0]);
resultList.add(row[1]);
}
} catch (IOException e) {
Log.e("Main", e.getMessage());
} finally {
try {
inputStream.close();
} catch (IOException e) {
Log.e("Main", e.getMessage());
}
}
return resultList;
}
}
}
productadapter.java
public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {
private Map<Integer, Integer> mSpinnerSelectedItem = new HashMap<Integer, Integer>();
private Map<String, String> numberItemValues = new HashMap<>();
// private SearchableSpinner spinner;
//we are storing all the products in a list
private List<Product> productList;
private Activity create;
//TODO CODE FOR CSV FILE
/*InputStream inputStream = getResources().openRawResource(R.raw.shopitems);
CSVFile csvFile = new CSVFile(inputStream);
final List<String> mSpinnerItems = csvFile.read();*/
InputStream inputStream = null;
List<String> mSpinnerItems = null;
CSVFile csvFile = null;
//TODO END OF CODE FOR CSV FILE
public ProductAdapter(Activity activity) {
create = activity;
}
//getting the context and product list with constructor
/*public ProductAdapter(Activity activity, List<Product> productList) {
// this.mCtx = mCtx;
*//* inputStream = create.getResources().openRawResource(R.raw.shopitems);
csvFile = new CSVFile(inputStream);
mSpinnerItems = csvFile.read();*//*
create = activity;
this.productList = productList;
}*/
public ProductAdapter(Activity activity, List<Product> productList, Map<String, String> numberList) {
numberItemValues = numberList;
create = activity;
this.productList = productList;
}
@Override
public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//inflating and returning our view holder
LayoutInflater inflater = LayoutInflater.from(create);
View view = inflater.inflate(R.layout.layout_products, null);
return new ProductViewHolder(view);
}
@Override
public void onBindViewHolder(final ProductViewHolder holder, final int position) {
// //getting the product of the specified position
ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(create, R.layout.item_spinner_layout,
Product.getSpinnerItemsList());
spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
holder.spinner.setAdapter(spinnerArrayAdapter);
holder.spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int mPosition, long id) {
mSpinnerSelectedItem.put(position, mPosition);
TextView mTextView = view.findViewById(R.id.mSpinnerText);
//TODO CODE FOR GETTING AISLE NUMBER AND PUTTING IT IN THE TEXTVIEW
/*String currentItem = mSpinnerItems.get(position);
String aisleNumber = numberItemValues.get(currentItem);
holder.textView5.setText(aisleNumber);
*/
//String currentItem = holder.spinner.getSelectedItem().toString();
String currentItem = holder.spinner.getItemAtPosition(mPosition).toString();
Set<String> set = numberItemValues.keySet(); for(String key : set) {String value = numberItemValues.get(key); Log.e("DATA ", "key = " + key + " value = " + value); }
//String currentItem = holder.spinner.getItemAtPosition(mPosition).toString();
String aisleNumber = numberItemValues.get(currentItem);
holder.textView5.setText(aisleNumber);
Log.e("SELECTION TEST", " Selected map item = " + aisleNumber );
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
//binding the data with the viewholder views
if (mSpinnerSelectedItem.containsKey(position)) {
holder.spinner.setSelection(mSpinnerSelectedItem.get(position));
}
holder.getView().setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(create);
// set title
alertDialogBuilder.setTitle("Delete Item");
// set dialog message
alertDialogBuilder
.setMessage("Are you sure you want to delete this item?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// if this button is clicked, close
// current activity
holder.checkBox.setChecked(false);
holder.spinner.setSelection(0);
productList.remove(holder.getAdapterPosition());
notifyItemRemoved(holder.getAdapterPosition());
Toast.makeText(create, "Item removed.", Toast.LENGTH_LONG).show();
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// if this button is clicked, just close
// the dialog box and do nothing
dialog.cancel();
}
});
// create alert dialog
AlertDialog alertDialog = alertDialogBuilder.create();
// show it
alertDialog.show();
}
});
}
@Override
public int getItemCount() {
return productList.size();
}
public void reset() {
productList.clear();
notifyDatasetChanged();
}
class ProductViewHolder extends RecyclerView.ViewHolder {
SearchableSpinner spinner;
EditText editText;
TextView textView5;
CheckBox checkBox;
LinearLayout linearLayout;
View rootView;
public ProductViewHolder(View itemView) {
super(itemView);
spinner = itemView.findViewById(R.id.spinner);
editText = itemView.findViewById(R.id.editText);
textView5 = itemView.findViewById(R.id.textView5);
checkBox = itemView.findViewById(R.id.checkBox);
rootView = itemView.findViewById(R.id.linearLayout);
checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// makes the set disappear when checkbox is ticked.
if(isChecked){
checkBox.setChecked(false);
spinner.setSelection(0);
productList.remove(getAdapterPosition());
notifyItemRemoved(getAdapterPosition());
Toast.makeText(create, "Done!", Toast.LENGTH_LONG).show();
}
}
});
}
public View getView() {
return rootView;
}
}
//TODO CODE FOR CSV FILE
private class CSVFile {
InputStream inputStream;
public CSVFile(InputStream inputStream) {
this.inputStream = inputStream;
}
public List<String> read() {
List<String> resultList = new ArrayList<String>();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
String line;
while ((line = reader.readLine()) != null) {
String[] row = line.split(",");
numberItemValues.put(row[1], row[0]);
resultList.add(row[1]);
}
} catch (IOException e) {
Log.e("Main", e.getMessage());
} finally {
try {
inputStream.close();
} catch (IOException e) {
Log.e("Main", e.getMessage());
}
}
return resultList;
}
}
}
答案 0 :(得分：3)
是的，您应该清除列表并致电adapter.notifyDataSetChanged()
upd
将此添加到适配器类中
public void reset() {
productList.clear();
notifyDataSetChanged();
}
如果您的适配器变量未声明为类可见变量，则可以按以下方式调用此函数
((YourAdapterClassName) yourRecyclerView.getAdapter()).reset()
在您的情况下，它应该看起来像
floatingActionButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
((ProductAdapter) recyclerView.getAdapter()).reset();
//Handle the empty adapter here
}
});
适配器应包含我之前编写的函数（无效重置）
如果您想向您的RecyclerView中添加新产品 您必须创建下一个功能
public void addNewProduct(Product product){
productList.add(product);
notifyDataSetChanged()
}
并调用它与重置功能相同
您的简化班>>
public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {
//we are storing all the products in a list
private List<Object> productList;
public ProductAdapter(Activity activity) {
}
public ProductAdapter(Activity activity, List<Object> productList, Map<String, String> numberList) {
this.productList = productList;
}
@Override
public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//inflating and returning our view holder
View view = new View(parent.getContext());
return new ProductViewHolder(view);
}
@Override
public void onBindViewHolder(final ProductViewHolder holder, final int position) {
}
@Override
public int getItemCount() {
return productList.size();
}
public void reset() {
productList.clear();
notifyDataSetChanged();
}
public void addNewProduct(Object product){
productList.add(product);
notifyDataSetChanged();
}
class ProductViewHolder extends RecyclerView.ViewHolder {
View rootView;
public ProductViewHolder(View itemView) {
super(itemView);
}
public View getView() {
return rootView;
}
}
}