当用户按下晶圆厂时，我的应用程序基本上会动态添加cardviews。当用户按下特定的cardview时，该cardview被删除。
cardviews内各有一个checkbox。我正在尝试这样做，以便当用户按下checkbox时，cardview也被删除。
所以我已经完成了
checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// makes the set disappear when checkbox is ticked.
productList.remove(position);
notifyItemRemoved(position);
Toast.makeText(create, "Done!",Toast.LENGTH_LONG).show();
}
});
但是我得到了这个错误：
java.lang.NullPointerException
at com.app.supermarketaislefinder.ProductAdapter.onBindViewHolder(ProductAdapter.java:159)
at com.app.supermarketaislefinder.ProductAdapter.onBindViewHolder(ProductAdapter.java:29)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6673)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6714)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5647)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5913)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5752)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5748)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2232)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1559)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1519)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:614)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3812)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3529)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:4082)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:948)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1855)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.support.v7.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:443)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1655)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1513)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1426)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
at android.view.View.layout(View.java:13856)
at android.view.ViewGroup.layout(ViewGroup.java:4424)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1992)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1813)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1113)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4481)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4867)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1007)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:774)
at dalvik.system.NativeStart.main(Native Method)
第29行是public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {
第159行是checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
我该如何解决？
产品适配器
public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {
private Map<Integer, Integer> mSpinnerSelectedItem = new HashMap<Integer, Integer>();
//this context we will use to inflate the layout
CheckBox checkBox;
//private Context mCtx;
private SearchableSpinner spinner;
//we are storing all the products in a list
private List<Product> productList;
private Activity create;
public ProductAdapter(Activity activity){
create = activity;
}
//getting the context and product list with constructor
public ProductAdapter(Activity activity, List<Product> productList) {
// this.mCtx = mCtx;
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(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);
/* Toast.makeText(create, "Selected Item: " + mTextView.getText().toString(), Toast.LENGTH_LONG).show();
Log.e("***************", "Selected Item: " + mTextView.getText().toString());*/
}
@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
productList.remove(position);
notifyItemRemoved(position);
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();
}
});
//checkbox ticked
checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// makes the set disappear when checkbox is ticked.
productList.remove(position);
notifyItemRemoved(position);
Toast.makeText(create, "Done!",Toast.LENGTH_LONG).show();
}
});
}
@Override
public int getItemCount() {
return productList.size();
}
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);
}
public View getView() {
return rootView;
}
}
}
答案 0 :(得分：2)
看到您犯了一个愚蠢的错误。您声明上面没有定义的signupValid并将Checkbox设置为该OnChangedList。.
CheckBox答案 1 :(得分：1)
您应使用上述解决方案。您应该在onBindViewHolder的{{1}}方法中使用它。像这样
Adapter