爲什麼adapter.clear（）清除這兩個適配器和ArrayList

Question

在該活動中，我獲取的所有聯繫人，並在listView顯示，有一個EditText搜索聯繫人一樣，如果我寫「妮」，那麼listView將顯示所有以「ni」開頭的聯繫人。爲此，我使用adapter.clear()和adapter.addAll(matchedContacts，所有聯繫人都以「ni」開頭）。但這裏的問題是，adapter.clear()的每一個電話正在清除contactList（其中我已經存儲所有聯繫人）並填寫matchedContacts的主要聯繫人列表，因爲如果我更改EditTextlistView未填充新聯繫人。

下面是代碼：

public class AddPerson2 extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_addperson2); 

     EditText searchContact = (EditText)findViewById(R.id.contact_search); 
     final ListView listView = (ListView)findViewById(R.id.contact_list); 
     final ArrayList<String[]> contactList = new ArrayList<>(); 

     ContentResolver contentResolver = getContentResolver(); 
     Cursor cursor = contentResolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, 
       new String[]{ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME 
         , ContactsContract.CommonDataKinds.Phone.NUMBER} 
       , null, null, ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME + " ASC"); 
     if (cursor != null){ 
      if (cursor.getCount() > 0){ 
       while (cursor.moveToNext()){ 
        String[] contact = new String[2]; 
        contact[0] = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME)); 
        contact[1] = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER)); 
        contactList.add(contact); 
       } 
      } 
     } 

     final ContactListAdapter contactListAdapter = new ContactListAdapter(this, contactList); 
     listView.setAdapter(contactListAdapter); 

     searchContact.addTextChangedListener(new TextWatcher() { 
      @Override 
      public void beforeTextChanged(CharSequence s, int start, int count, int after) { 

      } 

      @Override 
      public void onTextChanged(CharSequence s, int start, int before, int count) { 

      } 

      @Override 
      public void afterTextChanged(Editable s) { 
       String startingCharacter = s.toString().toLowerCase(); 

       ArrayList<String[]> matchedContacts = new ArrayList<>(); 

       for (String[] contact : contactList) { 
        if (contact[0].toLowerCase().startsWith(startingCharacter)){ 
         matchedContacts.add(contact); 
        } 
       } 

       contactListAdapter.clear(); 
       contactListAdapter.addAll(matchedContacts); 
      } 
     }); 

     listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
      @Override 
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
       view.setBackgroundColor(getResources().getColor(R.color.personSelectBackground)); 
       Log.wtf("showid", id+""); 
      } 
     }); 
    } 
} 

Answer 1

如果ContactListAdapter是ArrayAdapter，然後clear()被表現爲預期：

• 它調用底層ArrayList上clear()，從而排空
• 它請撥打notifyDataSetChanged()附上AdapterView，讓它知道數據中的變化

也許你想在適配器上使用過濾，在適配器上調用getFilter().filter()。 This sample app演示了這一點，儘管我使用的是SearchView而不是EditText。