我有一個片段:機器人 - 在片段的方法是不能訪問聲明的變量前面
public class VertretungsplanTab extends Fragment implements MainActivity.VertDataInterface{
TextView vertretungsView;
String LOG_TAG = VertretungsplanTab.class.getSimpleName();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.vertretungsplan_fragment, container,false);
vertretungsView = (TextView) rootView.findViewById(R.id.textView2);
vertretungsView.setText("initialised");
return rootView;
}
@Override
public void onRefreshed(Fragment tab,String data){
Log.v(LOG_TAG, "interface is working");
if(vertretungsView!=null) {
vertretungsView.setText(data);
}
else{
Log.e(LOG_TAG, "TextView is null object");
}
}
}
界面代碼是這樣的MainActivity:
public class MainActivity extends AppCompatActivity {
VertDataInterface mdataInterface;
private Fragment Vertretungstab;
public interface VertDataInterface {
public void onRefreshed(Fragment tab,String data);
}
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
Vertretungstab = mSectionsPagerAdapter.getItem(1);
try {
mdataInterface = (VertDataInterface) Vertretungstab;
} catch (ClassCastException e) {
Log.e(LOG_TAG, e + " fragment must implement VertDataInterface");
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_refresh) {
mdataInterface.onRefreshed(Vertretungstab,"cool");
return true;
}
return super.onOptionsItemSelected(item);
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
DashboardTab tabDashboard = new DashboardTab();
return tabDashboard;
case 1:
VertretungsplanTab tabVertretungsplan = new VertretungsplanTab();
return tabVertretungsplan;
default:
return null;
}
}
@Override
public int getCount() {
// Show 2 total pages.
return 2;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Dashboard";
case 1:
return "Vertretungsplan";
}
return null;
}
}
}
而且我有一個問題: 爲什麼我無法在我的界面中訪問我的TextView。爲什麼我可以在onCreate方法中設置文本,爲什麼它只能在界面方法中獲得空對象引用?
長時間搜索互聯網後,如果有更高級的開發人員可以獲得解決方案,我會很高興!
請提供您的界面代碼 –
我沒有看到您的界面方法在這裏。我認爲你做了錯誤的事情。 –
嘗試在VertretungsplanTab類中的onRefreshed方法之前添加@Override註釋 –