ListView在Android中，当Firebase数据库更新时，数值重复复制数值。

huangapple
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英文:

ListView Value duplicating the value when the firebase database is updated in Android

问题

以下是你提供的代码的翻译部分：

ListOfFaculty

  1. public class ListOfFaculty extends Fragment {
  3.     DatabaseReference ref;
  4.     ListView listview;
  5.     List<String> store;
  6.     List<String> UserID;
  7.     String[] faculty_list;
  8.     String a;
  10.     @Override
  11.     public void onCreate(Bundle savedInstanceState) {
  12.         super.onCreate(savedInstanceState);
  13.         ref = FirebaseDatabase.getInstance().getReference("Faculty");
  14.     }
  16.     @Override
  17.     public View onCreateView(LayoutInflater inflater, ViewGroup container,
  18.                              Bundle savedInstanceState) {
  19.         // Inflate the layout for this fragment
  20.         final View root = inflater.inflate(R.layout.fragment_list_of_faculty, container, false);
  22.         listview = root.findViewById(R.id.lv);
  23.         store = new ArrayList<>();
  24.         UserID = new ArrayList<>();
  26.         ref.addValueEventListener(new ValueEventListener() {
  28.             @Override
  29.             public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
  30.                 for (DataSnapshot postsap : dataSnapshot.getChildren()) {
  32.                     DataSnapshot data = postsap.child("name");
  33.                     if (data.exists()) {
  34.                         a = data.getValue().toString();
  35.                     }
  36.                     store.add(a);
  37.                     String Id = postsap.getKey();
  38.                     UserID.add(Id);
  39.                 }
  41.                 faculty_list = new String[store.size()];
  43.                 for (int i = 0; i < faculty_list.length; i++) {
  44.                     faculty_list[i] = store.get(i);
  45.                 }
  46.                 if (getActivity() != null) {
  47.                     ArrayAdapter<String> adapter = new ArrayAdapter<>(getContext(), android.R.layout.simple_spinner_item, faculty_list);
  48.                     listview.setAdapter(adapter);
  49.                 }
  50.             }
  52.             @Override
  53.             public void onCancelled(@NonNull DatabaseError databaseError) {
  55.             }
  56.         });
  58.         listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
  59.             @Override
  60.             public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
  62.                 Intent i = new Intent(getContext(), Faculty.class);
  63.                 i.putExtra("User_Id", UserID.get(position));
  64.                 startActivity(i);
  65.             }
  66.         });
  68.         listview.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
  69.             @Override
  70.             public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
  72.                 String name = faculty_list[position];
  73.                 Toast.makeText(getContext(), "" + UserID.get(position), Toast.LENGTH_SHORT).show();
  75.                 DialogFragment dialogFragment = new MyDailogFragment();
  76.                 Bundle bundle = new Bundle();
  77.                 bundle.putString("Name", name);
  78.               
  79.                 bundle.putString("Id", UserID.get(position));
  80.                 dialogFragment.setArguments(bundle);
  81.                 dialogFragment.show(getChildFragmentManager(), "missiles");
  83.                 return true;
  84.             }
  85.         });
  87.         return root;
  88.     }
  89. }

这是我的代码对你提供的Java代码的翻译。如果你有任何问题或需要进一步的帮助，请随时提问。

英文:

I have Listview in a Fragment in which i am setting data using ArrayAdapter, when i am deleting the data with Dialog box the Value is duplicating in the listview. i don't know what to do i was thinkint to refresh my fragment when the delete button is clicked in dialog box but i don't how to do that.I am new to Android please let me know what can i do to solve this.Here is my Code.

ListOfFaculty

  1. public class ListOfFaculty extends Fragment {
  3.     DatabaseReference ref;
  4.     ListView listview;
  5.     List&lt;String&gt; store;
  6.     List&lt;String&gt; UserID;
  7.     String[] faculty_list;
  8.     String a;
  10.     @Override
  11.     public void onCreate(Bundle savedInstanceState) {
  12.         super.onCreate(savedInstanceState);
  13.         ref = FirebaseDatabase.getInstance().getReference(&quot;Faculty&quot;);
  14.     }
  16.     @Override
  17.     public View onCreateView(LayoutInflater inflater, ViewGroup container,
  18.                              Bundle savedInstanceState) {
  19.         // Inflate the layout for this fragment
  20.         final View root =  inflater.inflate(R.layout.fragment_list_of_faculty, container, false);
  22.         listview = root.findViewById(R.id.lv);
  23.         store =new ArrayList&lt;&gt;();
  24.         UserID =new ArrayList&lt;&gt;();
  26.         ref.addValueEventListener(new ValueEventListener() {
  28.             @Override
  29.             public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
  30.                 for(DataSnapshot postsap : dataSnapshot.getChildren() ) {
  32.                     DataSnapshot data = postsap.child(&quot;name&quot;);
  33.                     if(data.exists()){
  34.                          a =  data.getValue().toString();
  35.                     }
  36.                     store.add(a);
  37.                     String Id = postsap.getKey();
  38.                     UserID.add(Id);
  39.                 }
  41.                 faculty_list = new String[store.size()];
  43.                 for(int i=0;i&lt;faculty_list.length;i++){
  44.                     faculty_list[i] =store.get(i);
  45.                 }
  46.                 if (getActivity() != null) {
  47.                     ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(getContext(), android.R.layout.simple_spinner_item, faculty_list);
  48.                     listview.setAdapter(adapter);
  49.                 }
  50.             }
  52.             @Override
  53.             public void onCancelled(@NonNull DatabaseError databaseError) {
  55.             }
  56.         });
  58.         listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
  59.             @Override
  60.             public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id) {
  62.                 Intent i = new Intent(getContext(),Faculty.class);
  63.                 i.putExtra(&quot;User_Id&quot;,UserID.get(position));
  64.                 startActivity(i);
  65.             }
  66.         });
  68.         listview.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
  69.             @Override
  70.             public boolean onItemLongClick(AdapterView&lt;?&gt; parent, View view, int position, long id) {
  72.                 String name = faculty_list[position];
  73.                 Toast.makeText(getContext(), &quot;&quot;+UserID.get(position), Toast.LENGTH_SHORT).show();
  75.                 DialogFragment dialogFragment =new MyDailogFragment();
  76.                 Bundle bundle =new Bundle();
  77.                 bundle.putString(&quot;Name&quot;,name);
  78.               
  79.                 bundle.putString(&quot;Id&quot;,UserID.get(position));
  80.                 dialogFragment.setArguments(bundle);
  81.                 dialogFragment.show(getChildFragmentManager(),&quot;missiles&quot;);
  83.                 return true;
  84.             }
  85.         });
  87.         return root;
  88.     }
  89. }

This is my Dialog Box Code,I am calling this Dialog box with .setOnItemLongClickListener from my ListofFaculty fragment.

MyDailogFragment

  1. public class MyDailogFragment extends DialogFragment {
  3.     DatabaseReference dailog;
  4.     String Id;
  6.     @NonNull
  7.     @Override
  8.     public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
  10.         Bundle bundle = getArguments();
  11.         final String name=  bundle.getString(&quot;Name&quot;,&quot;&quot;);
  12.         Id = bundle.getString(&quot;Id&quot;,&quot;&quot;);
  14.         AlertDialog.Builder alertDialog = new AlertDialog.Builder(getActivity());
  15.         alertDialog.setMessage(&quot;Delete &quot;+name+ &quot; ?&quot;)
  16.                 .setPositiveButton(&quot;Delete&quot;, new DialogInterface.OnClickListener() {
  17.                     @Override
  18.                     public void onClick(DialogInterface dialog, int which) {
  19.                         Toast.makeText(getActivity(), &quot;&quot;+Id, Toast.LENGTH_SHORT).show();
  20.                         dailog = FirebaseDatabase.getInstance().getReference(&quot;Faculty&quot;).child(Id);
  21.                         dailog.addListenerForSingleValueEvent(new ValueEventListener() {
  22.                             @Override
  23.                             public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
  24.                                 dataSnapshot.getRef().removeValue();
  25.                                 Toast.makeText(getActivity(), name+&quot; Deleted Successfully &quot;, Toast.LENGTH_SHORT).show();
  26.                             }
  28.                             @Override
  29.                             public void onCancelled(@NonNull DatabaseError databaseError) {
  31.                             }
  32.                         });
  33.                     }
  34.                 })
  35.                 .setNegativeButton(&quot;Cancel&quot;, new DialogInterface.OnClickListener() {
  36.                     @Override
  37.                     public void onClick(DialogInterface dialog, int which) {
  38.                         Toast.makeText(getActivity(), &quot;Nothing&quot;, Toast.LENGTH_SHORT).show();
  39.                     }
  40.                 });
  42.         return alertDialog.create();
  43.     }
  44. }

答案1

得分: 0

你在有新值时必须清除旧数据

  1. ref.addValueEventListener(new ValueEventListener() {
  2.     @Override
  3.     public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
  4.         store.clear();
  5.         for(DataSnapshot postsap : dataSnapshot.getChildren() ){
  7.             DataSnapshot data = postsap.child("name");
  8.             if(data.exists()){
  9.                 a =  data.getValue().toString();
  10.             }
  12.             store.add(a);
  13.             String Id = postsap.getKey();
  14.             UserID.add(Id);
  15.         }
  17.         faculty_list = new String[store.size()];
  19.         for(int i=0;i<faculty_list.length;i++){
  20.             faculty_list[i] =store.get(i);
  21.         }
  22.         if (getActivity() != null) {
  23.             ArrayAdapter<String> adapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_spinner_item, faculty_list);
  24.             listview.setAdapter(adapter);
  25.         }
  26.     }
  28.     @Override
  29.     public void onCancelled(@NonNull DatabaseError databaseError) {
  31.     }
  32. });
英文:

You have to clear old data when have new value

  1. ref.addValueEventListener(new ValueEventListener() {
  2.             @Override
  3.             public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
  4.                 store.clear();
  5.                 for(DataSnapshot postsap : dataSnapshot.getChildren() ){
  7.                     DataSnapshot data = postsap.child(&quot;name&quot;);
  8.                     if(data.exists()){
  9.                         a =  data.getValue().toString();
  10.                     }
  12.                     store.add(a);
  13.                     String Id = postsap.getKey();
  14.                     UserID.add(Id);
  15.                 }
  17.                 faculty_list = new String[store.size()];
  19.                 for(int i=0;i&lt;faculty_list.length;i++){
  20.                     faculty_list[i] =store.get(i);
  21.                 }
  22.                 if (getActivity() != null) {
  23.                     ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(getContext(), android.R.layout.simple_spinner_item, faculty_list);
  24.                     listview.setAdapter(adapter);
  25.                 }
  28.             }
  30.             @Override
  31.             public void onCancelled(@NonNull DatabaseError databaseError) {
  33.             }
  34.         });

huangapple
  • 本文由 发表于 2020年9月9日 15:22:34
  • 转载请务必保留本文链接：https://go.coder-hub.com/63806621.html
  • android
  • android-listview
  • java
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