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[英]How to prevent opening a fragment in navigation drawer if that fragment is already opened
[英]Why is the fragment not opening in Navigation drawer?
我的 MainActivity.java 包含
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(MenuItem item) {
switch (item.getItemId())
{
case R.id.calendar:
fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.main_container, new Calender());
fragmentTransaction.commit();
getSupportActionBar().setTitle("Calender");
item.setChecked(true);
break;
// drawer.closeDrawers();
}
return true;
}
});
我的 Calender.java 包含
public class Calender extends android.support.v4.app.Fragment{
Activity a;
CalendarView calendar;
public Calender() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
a = new Activity();
a.setContentView(R.layout.fragment_calender);
initializeCalendar();
return inflater.inflate(R.layout.fragment_calender, container, false);
}
public void initializeCalendar() {
calendar = (CalendarView) a.findViewById(R.id.calendar);
// sets whether to show the week number.
calendar.setShowWeekNumber(false);
// sets the first day of week according to Calendar.
// here we set Monday as the first day of the Calendar
calendar.setFirstDayOfWeek(2);
//The background color for the selected week.
calendar.setSelectedWeekBackgroundColor(getResources().getColor(R.color.green));
//sets the color for the dates of an unfocused month.
calendar.setUnfocusedMonthDateColor(getResources().getColor(R.color.transparent));
//sets the color for the separator line between weeks.
calendar.setWeekSeparatorLineColor(getResources().getColor(R.color.transparent));
//sets the color for the vertical bar shown at the beginning and at the end of the selected date.
calendar.setSelectedDateVerticalBar(R.color.darkgreen);
//sets the listener to be notified upon selected date change.
calendar.setOnDateChangeListener(new OnDateChangeListener() {
@Override
public void onSelectedDayChange(CalendarView view, int year, int month, int day) {
Toast.makeText(a.getApplicationContext(), day + "/" + month + "/" + year, Toast.LENGTH_LONG).show();
}
});
}
}
我的片段有問題嗎? 還是在主要活動中? 請盡快幫助。應用程序打開但我嘗試單擊日歷按鈕的地方,沒有顯示任何內容。
為什么你的片段中有一個活動實例? 將您的 onCreateView 更改為:
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
View view = inflater.inflate(R.layout.content_main, parent, false);
calendar = (CalendarView) view.findViewById(R.id.calendar);
return view;
}
然后在 onViewCreated 方法中執行以下操作:
initializeCalendar();
確保 content_main 中日歷視圖的 ID 是日歷。
如果使用Navigation Architecture Component ,則不必手動將片段連接到抽屜MenuItem。 The system will automatically tie you MenuItem to specific fragment
如果menu/xyz_menu.xml
中的MenuItem的ID與navigation/xyz_nav.xml
中的目標的ID相匹配,則NavController可以導航至該目標。
請遵循官方文檔中提到的正確步驟: https : //developer.android.com/guide/navigation/navigation-ui#Tie-navdrawer
注意:他們有一個示例應用程序鏈接到您可以參考的同一篇文章。
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