TabLayout使用

AFragment

package com.bwie.zhaojunhui20181113;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class AFragment extends Fragment {

    private TabLayout tabLayout;
    private ViewPager viewPager;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment01, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        tabLayout = view.findViewById(R.id.app_tab);
        viewPager = view.findViewById(R.id.viewPager);

        viewPager.setAdapter(new TabPagerAdapter(getChildFragmentManager()));
        tabLayout.setupWithViewPager(viewPager);

    }

}

fragment01.xml布局

<?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"
    android:background="#ffffcc"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

   <android.support.design.widget.TabLayout
       android:id="@+id/app_tab"
       android:layout_width="0dp"
       android:layout_height="wrap_content"
       app:layout_constraintLeft_toLeftOf="parent"
       app:layout_constraintRight_toRightOf="parent"
       app:tabMode="scrollable"
       />

    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/app_tab"
        app:layout_constraintBottom_toBottomOf="parent"
        />


</android.support.constraint.ConstraintLayout>

TabAdapter适配器

package com.bwie.zhaojunhui20181113;

import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.PagerAdapter;

public class TabPagerAdapter extends FragmentPagerAdapter {

    private String[] pageName = new String[]{"关注","推荐","热点"};

    public TabPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int i) {
        switch (i) {
            case 0:
                return new Fragment_a();
            case 1:
                return new Fragment_b();
            case 2:
                return new Fragment_c();
             default:
                 return new Fragment_a();
        }
    }

    @Nullable
    @Override
    public CharSequence getPageTitle(int position) {
        return pageName[position];
    }

    @Override
    public int getCount() {
        return pageName.length;
    }
}