[移动开发]Android：TabLayoutt+ViewPager页签制作

页签就是下面这种东西了：

页签制作

1.在布局文件中声明：

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/test_home_tablayout"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        app:tabSelectedTextColor="@color/black"
        app:tabTextColor="@color/gray" />

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/test_home_viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

2.定义Fragment数组：

    private UserFragment userFragment=new UserFragment();
    private InfoFragment infoFragment=new InfoFragment();
    private CareFragment careFragment=new CareFragment();
    private Fragment[] fragments=new Fragment[]{userFragment,infoFragment,careFragment};

3.Java中获得TabLayout和ViewPager：

        tablayout = (TabLayout) view.findViewById(R.id.test_home_tablayout);
        viewPager = (ViewPager) view.findViewById(R.id.test_home_viewpager);

4.自定义适配器

 class MyPagerAdapter extends FragmentPagerAdapter {
 		//构造函数，传入FragmentManager
        public MyPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
//            return new BodyFragment(tabTitles[position]);
            return fragments[position];
        }

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

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

5.使用适配器：

		//	getChildFragmentManager()获得所有子Fragment的Manager
        MyPagerAdapter pagerAdapter = new MyPagerAdapter(this.getChildFragmentManager());
        Log.d(TAG, "onCreateView: "+"getChildFragmentManager is "+this.getChildFragmentManager());
        viewPager.setAdapter(pagerAdapter);
        tablayout.setupWithViewPager(viewPager);//必须在 viewPager.setAdapter()之后使用
        tablayout.setTabMode(TabLayout.MODE_SCROLLABLE);