在动态片段中滑动标签

Question

我想在动态生成的片段中实现滑动标签（它没有布局文件），但我不知道如何。我已经尝试了一些东西，达到了一些“结果”，我的意思是它向我显示了选项卡布局，但它不会“加载”片段。我怀疑问题出在声明中的视图寻呼机上。这是片段的代码：

public class fg_tabs extends Fragment {

LinearLayout root;

TabLayout tab_layout;
ViewPager view_pager;
PagerAdapter pager_adaper;

public fg_tabs() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    root = new LinearLayout(getActivity());
    root.setOrientation(LinearLayout.VERTICAL);

    tab_layout = new TabLayout(getActivity());
    view_pager = new ViewPager(getActivity());
    view_pager.setCurrentItem(2);

    tab_layout.addTab(tab_layout.newTab().setText("Penguins"));
    tab_layout.addTab(tab_layout.newTab().setText("North Wind"));
    tab_layout.addTab(tab_layout.newTab().setText("Dr Octavious Brine"));


    tab_layout.setTabGravity(Gravity.FILL);
    pager_adaper = new PagerAdapter(getFragmentManager(),tab_layout.getTabCount());

    view_pager.setAdapter(pager_adaper);
    view_pager.setOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tab_layout));

    tab_layout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            view_pager.setCurrentItem(tab.getPosition());
        }

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

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

        }
    });

    root.addView(tab_layout);
    return root;
}

}

你可能想看看我怎么称呼这个片段，看看那里有没有问题：

    fg_tabs tabs = new fg_tabs();
    FragmentManager fm= getSupportFragmentManager();
    fm.beginTransaction().replace(R.id.layout_frame,tabs).commit();

寻呼机适配器类：

公共类 PagerAdapter 扩展 FragmentStatePagerAdapter { 诠释n;

public PagerAdapter(FragmentManager fm,int n) {
    super(fm);
    this.n=n;
}


@Override
public Fragment getItem(int position) {
    if(position == 0)
        return new Penguins();

    if(position == 1)
        return new NorthWind();

    if(position == 2)
        return new DrOctaviousBrine();

    return null;
}

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

}

Answer 1

我想你忘了将ViewPager 添加到onCreateView 的视图中：

ViewGroup.LayoutParams params = LinearLayout.LayoutParams(
    ViewGroup.LayoutParams.MATCH_PARENT,
    ViewGroup.LayoutParams.MATCH_PARENT)
root.addView(view_pager, params);
return root;

Answer 2

我找到了问题的答案，问题是没有为 viewpager 设置参数，也没有给他一个 id，也没有将它添加到布局中。对于那些遇到同样问题的人，只需使用普通的滑动标签代码（https://www.youtube.com/watch?v=zcnT-3F-9JA）并记住您使用的是动态片段，因此您不能声明 xml。

import android.graphics.Color;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

public class fg_tabs extends Fragment {

    LinearLayout root;
    TabLayout tab_layout;
    ViewPager view_pager;
    PagerAdapter pager_adapter;

    public fg_tabs() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        root = new LinearLayout(getActivity());

        root.setOrientation(LinearLayout.VERTICAL);
        root.setBackgroundColor(Color.parseColor("#42f4e8"));

        tab_layout = new TabLayout(getActivity());

        tab_layout.addTab(tab_layout.newTab().setText("penguins"));
        tab_layout.addTab(tab_layout.newTab().setText("north wind"));
        tab_layout.addTab(tab_layout.newTab().setText("octavious brine"));
        root.addView(tab_layout);

        tab_layout.setTabGravity(Gravity.FILL);

        view_pager = new ViewPager(getActivity());
        view_pager.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.FILL_PARENT));
        view_pager.setId(View.generateViewId());
        root.addView(view_pager);

        pager_adapter = new PagerAdapter(getChildFragmentManager(),tab_layout.getTabCount());

        view_pager.setAdapter(pager_adapter);
        view_pager.setOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tab_layout));

        tab_layout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                view_pager.setCurrentItem(tab.getPosition());
            }

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

            }

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

            }
        });
        return root;
    }
}