[英]findViewById in nested Fragment
我正在嘗試在片段(R.layout.fragment_2_ble)中而不是主要活動布局(R.layout.activity_main)中顯示活動處理的結果。
因此,當我嘗試在fragment_2_ble中而不在activity_main中找到(R.id.devicelist)時遇到問題。
MainActivity.java:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//setButtonText();
ble_device_list_adapter = new ListAdapter();
ListView listView = (ListView) this.findViewById(R.id.deviceList);
listView.setAdapter(ble_device_list_adapter);
ble_scanner = new BLEScanner();
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
if (ble_scanning) {
ble_scanner.stopScanning();
}
BluetoothDevice device = ble_device_list_adapter.getDevice(position);
if (toast != null) {
toast.cancel();
}
Intent intent = new Intent(MainActivity.this, PeripheralControlActivity.class);
intent.putExtra(PeripheralControlActivity.EXTRA_NAME, device.getName());
intent.putExtra(PeripheralControlActivity.EXTRA_ID, device.getAddress());
startActivity(intent);
}
});
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
displaySelectedScreen(R.id.nav_data);
//ButterKnife.bind(this);
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
boolean logged = prefs.getBoolean("logged", false);
if (!logged) {
//Launch login activity
Intent intent = new Intent(this, LoginActivity.class);
startActivity(intent);
}
}
@Override
protected void onStart() {
super.onStart();
}
private void displaySelectedScreen(int itemId) {
//creating fragment object
Fragment fragment = null;
//initializing the fragment object which is selected
switch (itemId) {
case R.id.nav_data:
fragment = new DataFragment();
break;
case R.id.nav_BLE:
fragment = new BLEFragment();
break;
case R.id.nav_settings:
fragment = new SettingsFragment();
break;
}
//replacing the fragment
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.commit();
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
displaySelectedScreen(item.getItemId());
return true;
}
BLEFragment.java:
public class BLEFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//returning our layout file
return inflater.inflate(R.layout.fragment_2_ble, container, false);
}
有關如何解決此問題的任何想法?
我認為您缺少有關片段的概念。 如果listView在片段中,則應制作findViewById並在片段中設置OnClickListener。 像這樣:
public class BLEFragment extends Fragment {
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//returning our layout file
View view = inflater.inflate(R.layout.fragment_2_ble, container, false);
ListView list = (ListView) view.findViewById(R.id.your_id);
list.setOnClickListenre(...);
return view;
}
}
在您的片段onCreateView()
您將獲得以下內容:
YOURLISTVIEW = (ListView) view.findViewById(R.id.deviceList);
在片段內部,您可以創建如下方法:
public ListView getListView(){
return YOURLISTVIEW;
}
然后主要是您將有一個片段實例。
您可以從片段訪問ListView
。
myFragment.getListView();
我將補充一點,如果此活動是片段的父級,則findViewById(R.id.fragmentITEM)
應該可以工作。
默認情況下,您無法實現這種結構。 創建時在活動中找不到片段UI元素。
在活動中創建onCreate視圖時未創建Becoz片段UI元素。
您可以在此鏈接中找到簡短的答案: 是否可以從activitiy的onCreate中訪問片段的UI元素
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