[英]How to delete listview item in fragment?
我正在尝试从列表视图中删除项目,但是有一个问题..我正在使用片段,我不知道如何获取“删除图像按钮”来添加onClickListener ...这就是我的xml在payment_list_view.xml中的删除按钮:
<ImageButton
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="@drawable/trash_icon"
android:padding="10dp"
android:id="@+id/delete_payment_btn"
android:background="@android:color/white" />
然后,我有我的PaymentFragment,其中包含我的列表视图:
package com.nicola.baccillieri.splitpayment;
public class PaymentFragment extends Fragment {
private String descString;
private int price;
private String payedBy;
private ArrayList<String> descPayArray;
private ArrayList<Integer> priceArray;
private ArrayList<String> payedByArray;
int trash;
PaymentAdapter customAdapter;
private final static String SHARED_PREFS = "sharedPrefs";
FirebaseFirestore db;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
db = FirebaseFirestore.getInstance();
trash = (R.drawable.trash_icon);
descPayArray = new ArrayList<>();
priceArray = new ArrayList<>();
payedByArray = new ArrayList<>();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View rootView=inflater.inflate(R.layout.payments_fragment,container,false);
ProgressBar detailsPb = rootView.findViewById(R.id.details_pb);
detailsPb.getIndeterminateDrawable().setColorFilter(0XFF3F51B5,
PorterDuff.Mode.MULTIPLY);
detailsPb.setVisibility(View.VISIBLE);
final ListView listView = rootView.findViewById(R.id.paymentLv);
String email = getEmail();
String groupName = getActivity().getIntent().getStringExtra("title");
DocumentReference docRef = db.collection("users").document(email).collection("Group").document(groupName);
docRef.collection("Payments")
.get()
.addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
@Override
public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
for (QueryDocumentSnapshot document : queryDocumentSnapshots) {
//Extracting payment description from each document
descString = document.getId();
descPayArray.add(descString);
//Extracting cost and who payed from each document
price = document.getLong("cost").intValue();
priceArray.add(price);
payedBy = document.getString("payed by");
payedByArray.add(payedBy);
trash = R.drawable.trash_icon;
customAdapter = new PaymentAdapter(getActivity(), descPayArray, payedByArray, priceArray, trash);
listView.setAdapter(customAdapter);
ProgressBar detailsPb = rootView.findViewById(R.id.details_pb);
detailsPb.setVisibility(View.GONE);
// That's the line that cause the error
ImageButton deleteBtn = rootView.findViewById(R.id.delete_payment_btn);
deleteBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String groupName = getActivity().getIntent().getStringExtra("title");
int positionToRemove = (int) v.getTag();
String email = getEmail();
String paymentToRemove = descPayArray.get(positionToRemove);
DocumentReference docRef = db.collection("users").document(email).collection("Group").document(groupName).collection("Payments").document(paymentToRemove);
docRef.delete();
descPayArray.remove(positionToRemove);
customAdapter.notifyDataSetChanged();
}
});
}
// If there isn't any payment display a blank activity
ProgressBar detailsPb = rootView.findViewById(R.id.details_pb);
detailsPb.setVisibility(View.GONE);
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
ProgressBar detailsPb = rootView.findViewById(R.id.details_pb);
detailsPb.setVisibility(View.GONE);
Toast.makeText(getContext(), "Failed to load payments", Toast.LENGTH_LONG).show();
}
});
return rootView;
}
public String getEmail() {
SharedPreferences sharedPreferences = this.getActivity().getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
String email = (sharedPreferences.getString("email", ""));
return email;
}}
最后,文件group_detail_activity.xml包含我的2个带有选项卡布局的片段。 现在,应用程序在必须显示PaymentFragment时崩溃,因为ImageButton deleteBtn = rootView.findViewById(R.id.delete_payment_btn); 说
`java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference".
那是因为我的rootView包含payment_fragment.xml,而不是payment_list_view.xml。 因此,它找不到该按钮。 我试图添加final View rootListView=inflater.inflate(R.layout.payment_list_view,container,false);
然后显示列表视图,但是当我单击删除按钮时,它什么也没做。 我该怎么办?
那就是我的PaymentAdapter:
package com.nicola.baccillieri.splitpayment;
public class PaymentAdapter extends BaseAdapter {
private Context context;
private ArrayList<String> payDesc;
private ArrayList<String> payedBy;
private ArrayList<Integer> price;
private int trash;
LayoutInflater inflater;
public PaymentAdapter(Context context, ArrayList<String> payDesc, ArrayList<String> payedBy, ArrayList<Integer> price, int trash) {
this.context = context;
this.payDesc = payDesc;
this.payedBy = payedBy;
this.price = price;
this.trash = trash;
inflater = (LayoutInflater.from(context));
}
@Override
public int getCount() {
return payDesc.size();
}
@Override
public Object getItem(int position) {
return payDesc.get(position);
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
convertView = inflater.inflate(R.layout.payment_list_view, null);
TextView paymentDesc = convertView.findViewById(R.id.payedDescTv);
TextView payedByTv = convertView.findViewById(R.id.payedByTv);
TextView priceTv = convertView.findViewById(R.id.priceTv);
ImageButton trashIcon = convertView.findViewById(R.id.delete_payment_btn);
paymentDesc.setText(payDesc.get(position));
payedByTv.setText("Payed by " + payedBy.get(position));
priceTv.setText(String.valueOf(price.get(position)) + "€");
trashIcon.setImageResource(trash);
trashIcon.setTag(position);
return convertView;
}}
问题是我需要同时从列表视图和Firebase中删除该项目...所以我需要getEmail()方法e PaymentExtra中的getExtra ..如果将侦听器放在适配器上,如何删除o火力基地?
尝试这种方式。 在列表上单击,您可以删除项目
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
payedByArray.remove(position);
adapter.notifyItemRemoved(position);
}
});
另一种方法是将“ Delete Button
放在您的payment_list_view
,然后在“适配器”中找到该按钮的位置,然后单击并删除它
从Custom_adapater的viewholder获取视图ID,您可以使用轻松删除该项目
payedByArray.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, payedByArray.size());
如何删除列表项 ,已经解决了一个SO问题。看一下……可能会解决您的问题。
您可以设置一个侦听器,以将“删除图像”按钮动作链接到您的片段。 然后可以单击按钮,触发监听器并执行片段中想要的操作。 可以发送职位删除好元素
您的适配器不知道该列表正在被修改。 您需要在删除项目后向适配器提供最新列表。
在适配器代码中公开您的payedByArray
列表。
此活动代码。
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
payedByArray.remove(position);
//payedByArray is activity list;
adapter.payedByArray = payedByArray;
adapter.notifyItemRemoved(position);
}
});
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