ViewPager 中未替换片段

Question

我正在尝试使用 TabLayout 和 ViewPager 替换选项卡中显示的片段，如下所示：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="in.netstreamtech.phonebuylogin.LoginRegisterActivity"
    android:paddingLeft="32.5dp"
    android:paddingTop="27dp"
    android:paddingRight="30dp">
    <LinearLayout
        android:id="@+id/main_layout"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <TextView
            android:id="@+id/signInReOtpHeader"
            android:layout_width="268dp"
            android:layout_height="122dp"
            android:includeFontPadding="true"
            android:maxLines="2"
            android:text="Welcome \nback."
            android:layout_gravity="center_vertical"
            android:textColor="#1aa4b8"
            android:textSize="35sp" />
        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="wrap_content"
            android:layout_height="47dp"
            android:minHeight="?attr/actionBarSize"
            android:elevation="6dp" />
        <!-- View pager to swipe views -->
        <android.support.v4.view.ViewPager
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>
</android.support.constraint.ConstraintLayout>

来自我的片段：

@Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof RegisterMainToActivity) {
            listener = (RegisterMainToActivity) context;
        }
    }    

然后在同一个片段中：

listener.passData(userRegistration);

界面：

public interface RegisterMainToActivity {
    void passData(UserRegistration data);
}

在我的活动中（LoginRegisterActivity）：

public class LoginRegisterActivity extends AppCompatActivity implements TabLayout.OnTabSelectedListener, RegisterMainToActivity {

    //This is our tablayout
    private TabLayout tabLayout;

    //This is our viewPager
    private ViewPager viewPager;

    private LoginPager adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login_register);


        //Initializing viewPager
        viewPager = (ViewPager) findViewById(R.id.pager);
        createViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabLayout);
        tabLayout.setupWithViewPager(viewPager);
        createTabIcons();

    }

    private void createTabIcons() {

        TextView tabOne = (TextView) LayoutInflater.from(this).inflate(R.layout.login_cutom_tab_view, null);
        tabOne.setText("SIGN IN");
        tabLayout.getTabAt(0).setCustomView(tabOne);

        TextView tabTwo = (TextView) LayoutInflater.from(this).inflate(R.layout.login_cutom_tab_view, null);
        tabTwo.setText("REGISTER");
        tabLayout.getTabAt(1).setCustomView(tabTwo);

    }

    private void createViewPager(ViewPager viewPager) {
        adapter = new LoginPager(getSupportFragmentManager());
        adapter.addFrag(new Login(), "SIGN IN");
        adapter.addFrag(new RegisterMain(), "REGISTER");
        viewPager.setAdapter(adapter);
    }

    @Override
    public void onTabSelected(TabLayout.Tab tab) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            //tabLayout.setBackground(getResources().getDrawable(R.drawable.login_tab_selected));
        }
    }

    @Override
    public void onTabUnselected(TabLayout.Tab tab) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            //tabLayout.setBackground(getResources().getDrawable(R.drawable.login_tab_unselected));
        }
    }

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

    }

    @Override
    public void passData(UserRegistration data) {
        RegisterOtp registerOtpFrag = new RegisterOtp();
        adapter.replaceFragment(registerOtpFrag, 1, "REGISTER");
        //adapter = new LoginPager(getSupportFragmentManager());
        //adapter.addFrag(new Login(), "SIGN IN");
        //adapter.addFrag(new RegisterOtp(), "REGISTER");
        //adapter.clearFragments();
        //adapter.addFrag(new Login(), "SIGN IN");
        //adapter.addFrag(new RegisterOtp(), "REGISTER");
        //viewPager.setAdapter(adapter);

        createTabIcons();
    }

//    public void attemptRegister(View v){
//        TextView registerName = (TextView) v.getContext()findViewById(R.id.register_name);
//        Toast.makeText(
//                getApplicationContext(),
//                registerName.getText(),
//                Toast.LENGTH_SHORT
//        ).show();
//    }


}

在函数 passData 中，我正在尝试替换片段。我希望将其添加到后台。

在我的适配器类中：

public class LoginPager extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public LoginPager(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {

        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFrag(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    public void replaceFragment(Fragment fragment, int index, String title) {
        mFragmentList.remove(index);
        mFragmentList.add(index, fragment);
        mFragmentTitleList.add(title);
        notifyDataSetChanged();
    }

    public void  clearFragments()
    {
        mFragmentList.clear();
        notifyDataSetChanged();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }

    @Override
    public int getItemPosition(Object object) {
        return this.POSITION_NONE;
    }
}

我尝试了许多变体，包括尝试清除适配器并重新创建片段。无论我做什么，我都无法替换所需的片段（RegisterMain 与 RegisterOtp）。理想情况下，我应该能够替换它...请帮助！！！

Answer 1

FragmentStatePagerAdapter 适合我。

public class LoginPager extends FragmentStatePagerAdapter {...}

FragmentPagerAdapter.notifyDataSetChanged() 没有清除那些已经提交的片段。

FragmentPagerAdapter 最适合在有少量 通常要分页的静态片段更多。