直接轉到導航抽屜中的片段Android

Question

我有一個導航抽屜活動，其中有片段。現在，如何在打開該活動時讓應用程序直接進入片段？我不想顯示content_main.xml（空白）：

Answer 1

你有一些選擇。

1）打開activity_main.xml

和替換線，包括layout=content_main與你真正想要的，而不是佈局。

2）只需加載片段onCreate，就像您點擊導航抽屜時一樣。

Answer 2

去活動onCreate方法，並把這個

FragmentManager fm =getFragmentManager(); 
FragmentTransaction ft= fm.beginTransaction(); 
// the Second paramter is Object from your Fragment that you want to add it 
ft.replace(R.id.activity_main ,fragmentObject ); 
ft.commit(); 

Answer 3

@Override 
public boolean onNavigationItemSelected(MenuItem item) { 

    //calling the method displayselectedscreen and passing the id of selected menu 
    displaySelectedScreen(item.getItemId()); 

    return true; 
} 

私人無效displaySelectedScreen（INT的itemId）{

//creating fragment object 
    Fragment fragment = null; 

    //initializing the fragment object which is selected 
    switch (itemId) { 
     case R.id.nav_menu1: 
      fragment = new Menu1(); 
      break; 
     case R.id.nav_menu2: 
      fragment = new Menu2(); 
      break; 
     case R.id.nav_menu3: 
      fragment = new Menu3(); 
      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); 
} 

中的onCreate（）

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); 

    //add this line to display menu1 when the activity is loaded 
    displaySelectedScreen(R.id.nav_menu1);