Question

在此活动中，我正在获取所有联系人并在listView中显示，并且有EditText来搜索联系人，例如，如果我写了＆＃34; ni＆＃34;然后listView将显示以＆＃34; ni＆＃34;开头的所有联系人。要这样做，我使用的是adapter.clear()和adapter.addAll(matchedContacts，所有联系人都会以＆＃34; ni＆＃34;）开始每次击键。但问题在于，adapter.clear()的每次调用都清除了contactList的主要联系人列表（我已存储了所有联系人）并填写matchedContacts，因为如果我更改EditText listView没有填充新联系人。

以下是代码：

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，则clear()的行为符合预期：

它会在基础clear()上调用ArrayList，从而将其清空
在附加的notifyDataSetChanged()上调用AdapterView，让其了解数据中的更改

也许您希望通过调用适配器上的getFilter().filter()来对适配器进行过滤。 This sample app证明了这一点，但我使用的是SearchView而不是EditText。

为什么adapter.clear（）清除适配器和arrayList

1 个答案: