ViewPager功能的前兩個頁面

Question

ViewPagerAdapter，我不明白的ViewPagerAdapter的行爲，我知道它創建一個向前的位置，從中選擇，例如，如果我選擇位置0在開始它返回我（ 0,1），我選擇1我返回（2），然後到達最後一個位置已經不會返回任何東西，因爲在理論上penuiltima並收取utlima位置，如果我處於位置1並且想要不再返回負載，因爲我想它已經加載了，如果我從位置0移動到最後一個位置返回加載（4和3）有什麼辦法來取消這種行爲或只加載你在沒有前進位置的位置

public class MainActivity extends Fragment { 
    private TabLayout tabLayout; 
    private ViewPager viewPager; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     Log.d("CONSOLE", "Main :::::::::: onCreateView"); 

     View rootView = inflater.inflate(R.layout.activity_main, container, false); 
     tabLayout = (TabLayout) rootView.findViewById(R.id.tablayout_menu); 
     viewPager = (ViewPager) rootView.findViewById(R.id.viewPager_menu); 

     tabLayout.addTab(tabLayout.newTab().setText("Tab 1")); 
     tabLayout.addTab(tabLayout.newTab().setText("Tab 2")); 
     tabLayout.addTab(tabLayout.newTab().setText("Tab 3")); 
     tabLayout.addTab(tabLayout.newTab().setText("Tab 4")); 
     tabLayout.addTab(tabLayout.newTab().setText("Tab 5")); 
     tabLayout.setTabGravity(TabLayout.GRAVITY_FILL); 
     CostumerFragment2 adapter = new CostumerFragment2(getActivity().getSupportFragmentManager()); 
     viewPager.setAdapter(adapter); 
     tabLayout.setupWithViewPager(viewPager); 

     return rootView; 
    } 

    public class CostumerFragment2 extends FragmentStatePagerAdapter { 

     public CostumerFragment2(FragmentManager fm) { 
      super(fm); 

     } 

     @Override 
     public Fragment getItem(int index) { 
      System.out.println("POSICION: " + index); 

      switch (index) { 
       case 0: 

        return new Fragment1(); 

       case 1: 

        return new Fragment2(); 
       case 2: 

        return new Fragment3(); 
       case 3: 

        return new Fragment4(); 
       case 4: 

        return new Fragment5(); 


      } 
      return null; 


     } 

     @Override 
     public int getCount() { 
      return 5; 
     } 

    } 

    @Override 
    public void onResume() { 
     super.onResume(); 
     Log.d("CONSOLE", "Main :::::::::: onResume"); 


    } 

    @Override 
    public void onPause() { 
     super.onPause(); 

     Log.d("CONSOLE", "Main :::::::::: onPause"); 
    } 

    @Override 
    public void onStart() { 
     super.onStart(); 
     Log.d("CONSOLE", "Main :::::::::: onStart"); 

    } 
} 

***新**

`

public class Principal extends AppCompatActivity { 
    private FrameLayout frameLayoutFragment; 
    private BottomNavigationView bottomNavigationView; 
    private AHBottomNavigation ahBottomNavigation; 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     Log.d("CONSOLE", "PAPA onCreate"); 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.principal); 

     frameLayoutFragment = (FrameLayout) findViewById(R.id.myFragemnt); 
     bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottomNavigation); 
     ahBottomNavigation = (AHBottomNavigation) findViewById(R.id.bottom_navigation); 

     final AHBottomNavigationItem item1 = new AHBottomNavigationItem("Menú", R.drawable.menu); 
     AHBottomNavigationItem item2 = new AHBottomNavigationItem("Favoritos", R.drawable.favoritos_item); 
     AHBottomNavigationItem item3 = new AHBottomNavigationItem("Tu orden", R.drawable.item_charola); 
     AHBottomNavigationItem item4 = new AHBottomNavigationItem("Perfil", R.drawable.item_perfil); 

     ahBottomNavigation.addItem(item1); 
     ahBottomNavigation.addItem(item2); 
     ahBottomNavigation.addItem(item3); 
     ahBottomNavigation.addItem(item4); 
     ahBottomNavigation.setBehaviorTranslationEnabled(false); 
     ahBottomNavigation.setAccentColor(R.color.colorAccent); 
     ahBottomNavigation.setInactiveColor(R.color.colorPrimary); 

     ahBottomNavigation.setForceTint(true); 
     ahBottomNavigation.setTranslucentNavigationEnabled(true); 

     ahBottomNavigation.setTitleState(AHBottomNavigation.TitleState.ALWAYS_SHOW); 
     ahBottomNavigation.setTitleState(AHBottomNavigation.TitleState.ALWAYS_SHOW); 

     ahBottomNavigation.setColored(false); 

     ahBottomNavigation.setCurrentItem(1); 

     ahBottomNavigation.setNotification("10", 1); 
     ahBottomNavigation.setOnTabSelectedListener(new AHBottomNavigation.OnTabSelectedListener() { 
      @Override 
      public boolean onTabSelected(int position, boolean wasSelected) { 
       // Do something cool here... 
       switch (position) { 
        case 0: 
         //item1.setColor(getResources().getColor(R.color.colorAccent)); 
         FragmentManager fm = getSupportFragmentManager(); 
         FragmentTransaction fragmentTransaction = fm.beginTransaction(); 

         MainActivity mainActivity = new MainActivity(); 
         fragmentTransaction.replace(R.id.myFragemnt, mainActivity); 
         fragmentTransaction.commit(); 

         return true; 
        case 1: 

         FragmentManager fm2 = getSupportFragmentManager(); 
         FragmentTransaction fragmentTransaction2 = fm2.beginTransaction(); 

         FragmentFavoritos fragmentFavoritos = new FragmentFavoritos(); 
         fragmentTransaction2.replace(R.id.myFragemnt, fragmentFavoritos); 
         fragmentTransaction2.commit(); 

         return true; 
        case 2: 
         FragmentManager fm3 = getSupportFragmentManager(); 
         FragmentTransaction fragmentTransaction3 = fm3.beginTransaction(); 

         FragmentOrden fragmentOrden = new FragmentOrden(); 
         fragmentTransaction3.replace(R.id.myFragemnt, fragmentOrden); 
         fragmentTransaction3.commit(); 

         return true; 
        case 3: 

         FragmentManager fm4 = getSupportFragmentManager(); 
         FragmentTransaction fragmentTransaction4 = fm4.beginTransaction(); 

         FragmentPerfil fragmentPerfil = new FragmentPerfil(); 
         fragmentTransaction4.replace(R.id.myFragemnt, fragmentPerfil); 
         fragmentTransaction4.commit(); 


         return true; 
       } 

       return true; 
      } 
     }); 

    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     Log.d("CONSOLE", "PAPA onResume"); 


    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     Log.d("CONSOLE", "PAPA onPause"); 
    } 

    @Override 
    protected void onStart() { 
     super.onStart(); 
     Log.d("CONSOLE", "PAPA onStart"); 

    } 
} 

`

Answer 1

爲了得到當前selected頁position：

mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { 
     @Override 
     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { 

     } 

     @Override 
     public void onPageSelected(int position) { 
      // Here position is the selected page-position 
     } 

     @Override 
     public void onPageScrollStateChanged(int state) { 

     } 
    }); 

2.轉到特定page：

viewPager.setCurrentItem(POSITION); 

變化page按Tab選擇：

tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() { 
     @Override 
     public void onTabSelected(TabLayout.Tab tab) { 
      // Change page 
      viewPager.setCurrentItem(tab.getPosition()); 
     } 

     @Override 
     public void onTabUnselected(TabLayout.Tab tab) { 

     } 

     @Override 
     public void onTabReselected(TabLayout.Tab tab) { 

     } 
    }); 

UPDATE：

＃。在你onCreateView()方法：

CostumerFragment2 adapter = new CostumerFragment2(getChildFragmentManager()); 

相反的：

CostumerFragment2 adapter = new CostumerFragment2(getActivity().getSupportFragmentManager()); 

＃。在CostumerFragment2添加以下方法：

@Override 
public int getItemPosition(Object object) { 

    return POSITION_NONE; 
} 

希望這將有助於〜